Android Programming Practicals

Question 1

Question

Create the standard calculator application in android:

AndroidManifest.xml   
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:tools="http://schemas.android.com/tools"> 
   <application 
       android:allowBackup="true" 
       android:dataExtractionRules="@xml/data_extraction_rules" 
       android:fullBackupContent="@xml/backup_rules" 
       android:icon="@mipmap/ic_launcher" 
       android:label="@string/app_name" 
       android:roundIcon="@mipmap/ic_launcher_round" 
       android:supportsRtl="true" 
       android:theme="@style/Theme.Calculator"> 
       <activity 
           android:name=".MainActivity" 
           android:exported="true"> 
           <intent-filter> 
               <action android:name="android.intent.action.MAIN" /> 
               <category android:name="android.intent.category.LAUNCHER" /> 
           </intent-filter> 
       </activity> 
   </application> 
</manifest> 

MainActivity.java 
package com.example.calculator1; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.TextView; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   private TextView tvResult; 
   private String currentInput = ""; 
   private double firstValue = 0.0; 
   private String operator = ""; 

   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       tvResult = findViewById(R.id.tvResult); 
       setOperatorListener(R.id.btnAdd, "+"); 
       setOperatorListener(R.id.btnSub, "-"); 
       setOperatorListener(R.id.btnMul, "*"); 
       setOperatorListener(R.id.btnDiv, "/"); 
       setOperatorListener(R.id.btnMod, "%"); 
       findViewById(R.id.btnClear).setOnClickListener(v -> { 
           currentInput = ""; 
           firstValue = 0.0; 
           operator = ""; 
           tvResult.setText("0"); 
       }); 
       findViewById(R.id.btnDel).setOnClickListener(v -> { 
           if (currentInput.length() > 0) { 
               currentInput = currentInput.substring(0, currentInput.length() - 1); 
               tvResult.setText(currentInput.isEmpty() ? "0" : currentInput); 
           } 
       }); 
       findViewById(R.id.btnEqual).setOnClickListener(v -> calculateResult()); 
   } 

   public void onDigitClick(View view) { 
       Button btn = (Button) view; 
       currentInput += btn.getText().toString(); 
       tvResult.setText(currentInput); 
   } 

   private void setOperatorListener(int btnId, String op) { 
       findViewById(btnId).setOnClickListener(v -> { 
           if (!currentInput.isEmpty()) { 
               firstValue = Double.parseDouble(currentInput); 
               operator = op; 
               currentInput = "";           } 
       }); 
   } 

   private void calculateResult() { 
       if (!currentInput.isEmpty() && !operator.isEmpty()) { 
           double secondValue = Double.parseDouble(currentInput); 
           double result = 0.0; 
           switch (operator) { 
               case "+": 
                   result = firstValue + secondValue; 
                   break; 
               case "-": 
                   result = firstValue - secondValue; 
                   break; 
               case "*": 
                   result = firstValue * secondValue; 
                   break; 
               case "/": 
                   result = firstValue / secondValue; 
                   break; 
               case "%": 
                   result = firstValue % secondValue; 
                   break; 
           } 
           tvResult.setText(String.valueOf(result)); 
           currentInput = String.valueOf(result); 
           operator = ""; 
       } 
   } 
} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:orientation="vertical" 
   android:padding="10dp" 
   android:background="#FFFFFF"> 
   <TextView 
       android:id="@+id/tvResult" 
       android:layout_width="match_parent" 
       android:layout_height="250dp" 
       android:background="#EEEEEE" 
       android:gravity="bottom|end" 
       android:padding="50dp" 
       android:text="0" 
       android:textColor="#000000" 
       android:textSize="48sp" /> 
   <GridLayout 
       android:layout_width="match_parent" 
       android:layout_height="0dp" 
       android:layout_weight="1" 
       android:columnCount="4" 
       android:rowCount="5" 
       android:layout_marginTop="10dp" 
       android:alignmentMode="alignMargins"> 
       <Button android:id="@+id/btnDel" android:text="DEL" style="@style/CalcBtn"/> 
       <Button android:id="@+id/btnClear" android:text="C" style="@style/CalcBtn"/> 
       <Button android:id="@+id/btnMod" android:text="%" style="@style/CalcBtn"/> 
       <Button android:id="@+id/btnAdd" android:text="+" style="@style/CalcBtn"/> 
       <Button android:text="1" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="2" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="3" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:id="@+id/btnDiv" android:text="/" style="@style/CalcBtn"/> 
       <Button android:text="4" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="5" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="6" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:id="@+id/btnSub" android:text="-" style="@style/CalcBtn"/> 
       <Button android:text="7" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="8" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="9" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:id="@+id/btnMul" android:text="X" style="@style/CalcBtn"/> 
       <Button android:text="." android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button android:text="0" android:onClick="onDigitClick" style="@style/CalcBtn"/> 
       <Button 
           android:id="@+id/btnEqual" 
           android:text="=" 
           style="@style/CalcBtn" 
           android:layout_columnSpan="2" 
           android:layout_gravity="fill_horizontal"/> 
   </GridLayout> 
</LinearLayout> 

Colors.xml 
<?xml version="1.0" encoding="utf-8"?> 
<resources> 
   <color name="black">#FF000000</color> 
   <color name="white">#FFFFFFFF</color> 
   <color name="teal_primary">#009688</color> 
   <color name="teal_dark">#00796B</color> 
   <color name="button_gray">#E0E0E0</color> 
</resources> 

Themes.xml 
<resources xmlns:tools="http://schemas.android.com/tools"> 
<style name="Base.Theme.Calculator" parent="Theme.AppCompat.Light.DarkActionBar"> 
   <item name="colorPrimary">@color/teal_primary</item> 
   <item name="colorPrimaryDark">@color/teal_dark</item> 
   <item name="colorAccent">@color/teal_primary</item> 
   <item name="titleTextColor">@color/white</item> 
</style> 
<style name="Theme.Calculator" parent="Base.Theme.Calculator" /> 
<style name="CalcBtn"> 
   <item name="android:layout_width">0dp</item> 
   <item name="android:layout_height">0dp</item> 
   <item name="android:layout_columnWeight">1</item> 
   <item name="android:layout_rowWeight">1</item> 
   <item name="android:textSize">20sp</item> 
   <item name="android:textStyle">bold</item> 
   <item name="android:layout_margin">6dp</item> 
   <item name="android:background">@color/button_gray</item> 
   <item name="android:textColor">@color/black</item> 
</style> 
</resources>

Question 2

Question

Create a login screen with EditText fields for username and password, and a Button to submit. Include validation for empty fields.

 
AndroidManifest.xml 
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   package="com.example.uielements"> 
   <application 
       android:allowBackup="true" 
       android:icon="@mipmap/ic_launcher" 
       android:label="@string/app_name" 
       android:roundIcon="@mipmap/ic_launcher_round" 
       android:supportsRtl="true" 
       android:theme="@style/Theme.UIElements"> 
       <activity android:name=".MainActivity" 
           android:exported="true"> 
           <intent-filter> 
               <action android:name="android.intent.action.MAIN" /> 
               <category android:name="android.intent.category.LAUNCHER" /> 
           </intent-filter> 
       </activity> 
   </application> 
</manifest> 

MainActivity.java 
package com.example.uielements; 
import android.os.Bundle; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 
import androidx.appcompat.app.AppCompatActivity; 
import androidx.appcompat.widget.Toolbar; 
import androidx.fragment.app.FragmentTransaction; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       Toolbar toolbar = findViewById(R.id.toolbar); 
       setSupportActionBar(toolbar); 
       EditText et_user_name = findViewById(R.id.et_user_name); 
       EditText et_password = findViewById(R.id.et_password); 
       Button btnReset = findViewById(R.id.btn_reset); 
       Button btnSubmit = findViewById(R.id.btn_submit); 
       btnReset.setOnClickListener(v -> { 
           et_user_name.setText(""); 
           et_password.setText(""); 
       }); 
       btnSubmit.setOnClickListener(v -> { 
           String uname = et_user_name.getText().toString().trim(); 
           String pwd = et_password.getText().toString().trim(); 
           if (uname.isEmpty()) { 
               et_user_name.setError("Username is required"); 
               et_user_name.requestFocus(); 
               return;            } 
           if (pwd.isEmpty()) { 
               et_password.setError("Password is required"); 
               et_password.requestFocus(); 
               return;            } 
           Toast.makeText(MainActivity.this, "Welcome " + uname, Toast.LENGTH_LONG).show(); 
       }); 
   }} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<androidx.coordinatorlayout.widget.CoordinatorLayout 
   xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:app="http://schemas.android.com/apk/res-auto" 
   xmlns:tools="http://schemas.android.com/tools" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   tools:context=".MainActivity"> 
   <com.google.android.material.appbar.AppBarLayout 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"> 
       <androidx.appcompat.widget.Toolbar 
           android:id="@+id/toolbar" 
           android:layout_width="match_parent" 
           android:layout_height="?attr/actionBarSize" 
           app:title="UI Elements Demo" 
           app:titleTextColor="@android:color/white" 
           app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/> 
   </com.google.android.material.appbar.AppBarLayout> 
   <LinearLayout 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:orientation="vertical" 
       android:padding="16dp" 
       android:layout_marginTop="80dp"> 
       <TextView 
           android:layout_width="wrap_content" 
           android:layout_height="wrap_content" 
           android:textSize="25sp" 
           android:text="Login" 
           android:layout_gravity="center_horizontal"/> 
       <com.google.android.material.textfield.TextInputLayout 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:layout_marginTop="16dp"> 
           <com.google.android.material.textfield.TextInputEditText 
               android:id="@+id/et_user_name" 
               android:layout_width="match_parent" 
               android:layout_height="wrap_content" 
               android:hint="Username" 
               android:inputType="textPersonName" /> 
       </com.google.android.material.textfield.TextInputLayout> 
       <com.google.android.material.textfield.TextInputLayout 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:layout_marginTop="16dp" 
           app:passwordToggleEnabled="true"> <com.google.android.material.textfield.TextInputEditText 
           android:id="@+id/et_password" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:hint="Password" 
           android:inputType="textPassword" /> 
       </com.google.android.material.textfield.TextInputLayout> 
       <LinearLayout 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:gravity="center" 
           android:orientation="horizontal" 
           android:layout_marginTop="16dp"> 
           <Button 
               android:id="@+id/btn_reset" 
               android:text="Reset" 
               android:layout_width="wrap_content" 
               android:layout_height="wrap_content" 
               android:layout_marginEnd="16dp"/> 
           <Button 
               android:id="@+id/btn_submit" 
               android:text="Submit" 
               android:layout_width="wrap_content" 
               android:layout_height="wrap_content"/> 
       </LinearLayout> 
       <FrameLayout 
           android:id="@+id/fragment_container" 
           android:layout_width="match_parent" 
           android:layout_height="0dp" 
           android:layout_weight="1" 
           android:layout_marginTop="16dp"/> 
   </LinearLayout> 
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Question 3

Question

Create an android application to display Alert Dialog on pressing the Back button.

MainActivity.java 
package com.example.alertdialogapp; 
import android.os.Bundle; 
import androidx.activity.OnBackPressedCallback; 
import androidx.appcompat.app.AlertDialog; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       // Create a callback to handle the back button press 
       OnBackPressedCallback callback = new OnBackPressedCallback(true) { 
           @Override 
           public void handleOnBackPressed() { 
               showExitDialog(); 
           } 
       }; 
       // Add the callback to the dispatcher 
       getOnBackPressedDispatcher().addCallback(this, callback); 
   } 
   private void showExitDialog() { 
       // Build the Alert Dialog 
       new AlertDialog.Builder(this) 
               .setTitle("Exit Application") 
               .setMessage("Are you sure you want to exit?") 
               .setCancelable(false) // Prevent closing by clicking outside 
               .setPositiveButton("Yes", (dialog, which) -> { 
                   // User clicked Yes, so close the activity 
                   finish(); 
               }) 
               .setNegativeButton("No", (dialog, which) -> { 
                   // User clicked No, so just close the dialog 
                   dialog.dismiss(); 
               }) 
               .show(); 
   } 
} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:gravity="center" 
   android:orientation="vertical"> 
   <TextView 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Press the Back Button to see the Alert" 
       android:textSize="18sp" 
       android:textStyle="bold" /> 
</LinearLayout>

Question 4

Question

Create an android application to display Alert Dialog on pressing the Back button.

Androidmanifest.xml 
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:tools="http://schemas.android.com/tools"> 

   <application 
       android:allowBackup="true" 
       android:dataExtractionRules="@xml/data_extraction_rules" 
       android:fullBackupContent="@xml/backup_rules" 
       android:icon="@mipmap/ic_launcher" 
       android:label="@string/app_name" 
       android:roundIcon="@mipmap/ic_launcher_round" 
       android:supportsRtl="true" 
       android:theme="@style/Theme.Datapassingapp"> 
       <activity 
           android:name=".MainActivity" 
           android:exported="true"> 
           <intent-filter> 
               <action android:name="android.intent.action.MAIN" /> 

               <category android:name="android.intent.category.LAUNCHER" /> 
           </intent-filter> 
       </activity> 
       <activity android:name=".SecondActivity" /> 
   </application> 

</manifest> 

MainActivity.java 
package com.example.datapassingapp; // TODO: Check your package name 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   // Declare variables 
   private EditText etInput; 
   private Button btnSend; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       // 1. Bind Views (These IDs match activity_main.xml) 
       etInput = findViewById(R.id.etInput); 
       btnSend = findViewById(R.id.btnSend); 
       // 2. Set Button Click Listener 
       btnSend.setOnClickListener(new View.OnClickListener() { 
           @Override 
           public void onClick(View v) { 
               // Get the string from the EditText 
               String message = etInput.getText().toString(); 
               // Create the Intent object (From Here -> To SecondActivity) 
               Intent intent = new Intent(MainActivity.this, SecondActivity.class); 
               // Pass the data (Key: "USER_MESSAGE", Value: message) 
               intent.putExtra("USER_MESSAGE", message); 
               // Start the new activity 
               startActivity(intent); 
           } 
       }); 
   } 
} 

SecondActivity.java 
package com.example.datapassingapp; // TODO: Check your package name 
import android.content.Intent; 
import android.os.Bundle; 
import android.widget.TextView; 
import androidx.appcompat.app.AppCompatActivity; 
public class SecondActivity extends AppCompatActivity { 
   private TextView tvResult; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_second); 
       // 1. Bind View (Matches activity_second.xml) 
       tvResult = findViewById(R.id.tvResult); 
       // 2. Get the Intent that started this activity 
       Intent intent = getIntent(); 
       // 3. Extract the string using the same Key "USER_MESSAGE" 
       if (intent != null) { 
           String receivedText = intent.getStringExtra("USER_MESSAGE"); 
           // Set the text to the TextView 
           tvResult.setText(receivedText); 
       } 
   } 
} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:orientation="vertical" 
   android:gravity="center" 
   android:padding="20dp"> 
   <EditText 
       android:id="@+id/etInput" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:hint="Type a message here" 
       android:textSize="18sp" /> 
   <Button 
       android:id="@+id/btnSend" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Send to Second Activity" 
       android:layout_marginTop="20dp" /> 

</LinearLayout> 

Activity_second.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:orientation="vertical" 
   android:gravity="center" 
   android:padding="20dp"> 
   <TextView 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Received Data:" 
       android:textSize="16sp" /> 
   <TextView 
       android:id="@+id/tvResult" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Waiting..." 
       android:textSize="24sp" 
       android:textStyle="bold" 
       android:layout_marginTop="10dp" 
       android:textColor="@android:color/holo_blue_dark"/> 
</LinearLayout>

Question 5

Question

Create a user interface with a TextView, Button, and ImageView. When the button is clicked, the image should be changed dynamically.

MainActivity.java 
package com.example.imagechanger; // TODO: Check your package name 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import android.widget.ImageView; 
import android.widget.TextView; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   // Declare View variables 
   private TextView tvStatus; 
   private ImageView ivDisplay; 
   private Button btnChange; 
   // Flag to track which image is currently showing 
   private boolean isImageOne = true; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       // 1. Initialize Views 
       tvStatus = findViewById(R.id.tvStatus); 
       ivDisplay = findViewById(R.id.ivDisplay); 
       btnChange = findViewById(R.id.btnChange); 
       // 2. Set Button Click Listener 
       btnChange.setOnClickListener(new View.OnClickListener() { 
           @Override 
           public void onClick(View v) { 
               if (isImageOne) { 
                   // Switch to second image 
                   ivDisplay.setImageResource(R.drawable.image_two); 
                   tvStatus.setText("Current Image: Two"); 
                   isImageOne = false; // Update flag 
               } else { 
                   // Switch back to first image 
                   ivDisplay.setImageResource(R.drawable.image_one); 
                   tvStatus.setText("Current Image: One"); 
                   isImageOne = true; // Update flag 
               } 
           } 
       }); 
   } 
} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:orientation="vertical" 
   android:gravity="center" 
   android:padding="20dp"> 
   <TextView 
       android:id="@+id/tvStatus" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Current Image: One" 
       android:textSize="22sp" 
       android:textStyle="bold" 
       android:layout_marginBottom="20dp"/> 
   <ImageView 
       android:id="@+id/ivDisplay" 
       android:layout_width="250dp" 
       android:layout_height="250dp" 
       android:src="@drawable/image_one" 
       android:scaleType="centerCrop" 
       android:layout_marginBottom="30dp"/> 
   <Button 
       android:id="@+id/btnChange" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Change Image" 
       android:padding="15dp"/> 
</LinearLayout>

Question 6

Question

Create the background service android application to play the ringtone/music.

   
AndroidManifest.xml 
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:tools="http://schemas.android.com/tools"> 

   <application 
       android:allowBackup="true" 
       android:dataExtractionRules="@xml/data_extraction_rules" 
       android:fullBackupContent="@xml/backup_rules" 
       android:icon="@mipmap/ic_launcher" 
       android:label="@string/app_name" 
       android:roundIcon="@mipmap/ic_launcher_round" 
       android:supportsRtl="true" 
       android:theme="@style/Theme.Backgroundmusic"> 
       <activity 
           android:name=".MainActivity" 
           android:exported="true"> 
           <intent-filter> 
               <action android:name="android.intent.action.MAIN" /> 
               <category android:name="android.intent.category.LAUNCHER" /> 
           </intent-filter> 
       </activity> 
       <service android:name=".MusicService" /> 
   </application> 

</manifest>

MainActivity.java 
package com.example.backgroundmusic; // TODO: Check your package name 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.widget.Button; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   Button btnStart, btnStop; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       btnStart = findViewById(R.id.btnStart); 
       btnStop = findViewById(R.id.btnStop); 
       // Listener to Start Service 
       btnStart.setOnClickListener(new View.OnClickListener() { 
           @Override 
           public void onClick(View v) { 
               Intent serviceIntent = new Intent(MainActivity.this, MusicService.class); 
               startService(serviceIntent); 
           } 
       }); 
       // Listener to Stop Service 
       btnStop.setOnClickListener(new View.OnClickListener() { 
           @Override 
           public void onClick(View v) { 
               Intent serviceIntent = new Intent(MainActivity.this, MusicService.class); 
               stopService(serviceIntent); 
           } 
       }); 
   } 
} 

MusicService.java 
package com.example.backgroundmusic; // TODO: Check your package name 
import android.app.Service; 
import android.content.Intent; 
import android.media.MediaPlayer; 
import android.os.IBinder; 
import android.provider.Settings; 
import android.widget.Toast; 
import androidx.annotation.Nullable; 
public class MusicService extends Service { 
   private MediaPlayer player; 
   @Override 
   @Nullable 
   public IBinder onBind(Intent intent) { 
       // We are not binding to an activity, so return null 
       return null; 
   } 
   @Override 
   public int onStartCommand(Intent intent, int flags, int startId) { 
       // 1. Create the MediaPlayer logic 
       if (player == null) { 
           // Use the default system ringtone 
           player = MediaPlayer.create(this, Settings.System.DEFAULT_RINGTONE_URI); 
           player.setLooping(true); // Loop the music 
       } 
       // 2. Start the player if it's not already playing 
       if (!player.isPlaying()) { 
           player.start(); 
           Toast.makeText(this, "Music Service Started", Toast.LENGTH_SHORT).show(); 
       } 
       // START_STICKY ensures the service restarts if the system kills it 
       return START_STICKY; 
   } 
   @Override 
   public void onDestroy() { 
       super.onDestroy(); 
       // 3. Cleanup: Stop and release the player when service is stopped 
       if (player != null) { 
           if (player.isPlaying()) { 
               player.stop(); 
           } 
           player.release(); 
           player = null; 
       } 
       Toast.makeText(this, "Music Service Stopped", Toast.LENGTH_SHORT).show(); 
   } 
}

Question 7

Question

Create an android application which automatically notify the user when Aeroplane mode is turned on or off using a broadcast receiver.

 
Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:orientation="vertical" 
   android:gravity="center" 
   android:padding="20dp"> 
   <TextView 
       android:id="@+id/tvInstruction" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Toggle Airplane Mode via your Quick Settings Panel to test." 
       android:textSize="18sp" 
       android:gravity="center" 
       android:layout_marginBottom="20dp"/> 
   <TextView 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="(Toast notification will appear)" 
       android:textSize="14sp" 
       android:textColor="#666666"/> 
</LinearLayout> 

MainActivity.java 
package com.example.airplanemodeapp; // TODO: Check your package name 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.os.Bundle; 
import android.widget.TextView; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   private AirplaneModeReceiver airplaneModeReceiver; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       // Initialize the receiver 
       airplaneModeReceiver = new AirplaneModeReceiver(); 
   } 
   @Override 
   protected void onStart() { 
       super.onStart(); 
       // 1. Create an IntentFilter for Airplane Mode 
       IntentFilter filter = new IntentFilter(Intent.ACTION_AIRPLANE_MODE_CHANGED); 
       // 2. Register the receiver dynamically 
       // This is required for Android 8.0 (Oreo) and above 
       registerReceiver(airplaneModeReceiver, filter); 
   } 
   @Override 
   protected void onStop() { 
       super.onStop(); 
       // 3. Unregister the receiver to save battery and prevent crashes 
       if (airplaneModeReceiver != null) { 
           unregisterReceiver(airplaneModeReceiver); 
       } 
   } 
} 

AirplaneModeReceiver.java 
package com.example.airplanemodeapp; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.os.CountDownTimer; 
import android.widget.Toast; 
public class AirplaneModeReceiver extends BroadcastReceiver { 
   @Override 
   public void onReceive(Context context, Intent intent) { 
       if (Intent.ACTION_AIRPLANE_MODE_CHANGED.equals(intent.getAction())) { 
           boolean isAirplaneModeOn = intent.getBooleanExtra("state", false); 
           String message = isAirplaneModeOn ? "Airplane Mode is ON " : "Airplane Mode is OFF "; 
           showCustomDurationToast(context, message, 10000); 
       } 
   } 
   private void showCustomDurationToast(Context context, String message, int durationInMillis) { 
       final Toast toast = Toast.makeText(context, message, Toast.LENGTH_SHORT); 
       new CountDownTimer(durationInMillis, 1000) { 

           public void onTick(long millisUntilFinished) { 
               toast.show(); 
           } 
           public void onFinish() { 
               // Ensure the toast disappears when time is up 
               toast.cancel(); 
           } 
       }.start(); 
   } 
}

Question 8

Question

Explain the Android Activity life cycle in detail. Implement a simple app that logs the lifecycle methods (onCreate(), onStart(), onResume(), onPause(), onStop(), onDestroy())

MainActivity.java 
package com.example.lifecyclelogger; // TODO: Check your package name 
import android.os.Bundle; 
import android.util.Log; 
import android.widget.TextView; 
import androidx.appcompat.app.AppCompatActivity; 
public class MainActivity extends AppCompatActivity { 
   // Tag for filtering logs in Android Studio 
   private static final String TAG = "LifecycleEvent"; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 

       Log.d(TAG, "onCreate() called: Activity Initialized"); 
   } 
   @Override 
   protected void onStart() { 
       super.onStart(); 
       Log.d(TAG, "onStart() called: Activity is becoming visible"); 
   } 
   @Override 
   protected void onResume() { 
       super.onResume(); 
       Log.d(TAG, "onResume() called: Activity is interactive (Top of stack)"); 
   } 
   @Override 
   protected void onPause() { 
       super.onPause(); 
       Log.d(TAG, "onPause() called: User is leaving (or app partially obscured)"); 
   } 
   @Override 
   protected void onStop() { 
       super.onStop(); 
       Log.d(TAG, "onStop() called: Activity is no longer visible"); 
   } 
   @Override 
   protected void onRestart() { 
       super.onRestart(); 
       Log.d(TAG, "onRestart() called: Activity returning from stopped state"); 
   } 
   @Override 
   protected void onDestroy() { 
       super.onDestroy(); 
       Log.d(TAG, "onDestroy() called: Activity is being destroyed"); 
   } 
}

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:gravity="center" 
   android:orientation="vertical"> 
   <TextView 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Check Logcat for 'LifecycleEvent'" 
       android:textSize="20sp" 
       android:textStyle="bold" /> 
</LinearLayout>

Question 9

Question

Create a simple Hello World application in Android Studio. Explain the purpose of the MainActivity and the activity_main.xml file.

 
MainActivity.java 
package com.example.helloworld; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<androidx.constraintlayout.widget.ConstraintLayout 
   xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:app="http://schemas.android.com/apk/res-auto" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent">
   <TextView 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Hello World!" 
       app:layout_constraintTop_toTopOf="parent" 
       app:layout_constraintBottom_toBottomOf="parent" 
       app:layout_constraintStart_toStartOf="parent" 
       app:layout_constraintEnd_toEndOf="parent"/> 
</androidx.constraintlayout.widget.ConstraintLayout>

Question 10

Question

Create an android application to demonstrate the following event listeners on the following widgets: Button: on click listener, long click listener Image: Touch listener with these motion events :Action up, action down and action pointer down Edit Text : key listener on Enter key The Appropriate message should be displayed in text view.

 
MainActivity.java 
package com.example.eventlistenersdemo; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.KeyEvent; 
import android.view.MotionEvent; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.ImageView; 
import android.widget.TextView; 
public class MainActivity extends AppCompatActivity { 
   Button btnClick; 
   ImageView imageView; 
   EditText editText; 
   TextView textView; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       btnClick = findViewById(R.id.btnClick); 
       imageView = findViewById(R.id.imageView); 
       editText = findViewById(R.id.editText); 
       textView = findViewById(R.id.textView); 
       btnClick.setOnClickListener(v -> 
               textView.setText("Button Clicked")); 
       btnClick.setOnLongClickListener(v -> { 
           textView.setText("Button Long Pressed"); 
           return true; 
       }); 
       imageView.setOnTouchListener((v, event) -> { 
           switch (event.getAction()) { 
               case MotionEvent.ACTION_DOWN: 
                   textView.setText("Image Action Down"); 
                   break; 
               case MotionEvent.ACTION_UP: 
                   textView.setText("Image Action Up"); 
                   break; 
               case MotionEvent.ACTION_POINTER_DOWN: 
                   textView.setText("Pointer Down (Multiple Fingers)"); 
                   break; 
           } 
           return true; 
       }); 
       editText.setOnKeyListener((v, keyCode, event) -> { 
           if (event.getAction() == KeyEvent.ACTION_DOWN && 
               keyCode == KeyEvent.KEYCODE_ENTER) { 
               textView.setText("Enter Key Pressed"); 
               return true; 
           } 
           return false; 
       }); 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:app="http://schemas.android.com/apk/res-auto" 
   android:orientation="vertical" 
   android:padding="20dp" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <ImageView 
       android:id="@+id/imageView" 
       android:layout_width="100dp" 
       android:layout_height="100dp" 
       android:src="@mipmap/ic_launcher" 
       app:layout_constraintTop_toTopOf="parent" 
       app:layout_constraintBottom_toBottomOf="parent" 
       app:layout_constraintStart_toStartOf="parent" 
       app:layout_constraintEnd_toEndOf="parent" /> 
   <EditText 
       android:id="@+id/editText" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="20dp" 
       android:hint="Press Enter Key" /> 
   <TextView 
       android:id="@+id/textView" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="20dp" 
       android:text="Event Message Will Appear Here" 
       android:textSize="18sp" /> 
   <Button 
       android:id="@+id/btnClick" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:text="Click or Long Press Me" /> 
</LinearLayout>

Question 11

Question

Implement a custom color scheme for your registration form. Set the background color of the entire layout to a light color, and use a contrasting color for the Submit button.

 
colors.xml 
<resources> 
   <color name="light_bg">#B9FF00</color> 
   <color name="submit_color">#000000</color> 
   <color name="white">#FFFFFF</color> 
</resources> 

activity_main 
<?xml version="1.0" encoding="utf-8"?> 
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:app="http://schemas.android.com/apk/res-auto" 
   xmlns:tools="http://schemas.android.com/tools" 
   android:id="@+id/main" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   tools:context=".MainActivity"> 

   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       android:orientation="vertical" 
       android:padding="20dp" 
       android:background="@color/light_bg"> 

       <EditText 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:hint="Name" /> 

       <EditText 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:hint="Email" 
           android:layout_marginTop="10dp" /> 

       <Button 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content" 
           android:text="Submit" 
           android:textColor="@color/white" 
           android:backgroundTint="@color/submit_color" 
           android:layout_marginTop="20dp" /> 

   </LinearLayout> 

</androidx.constraintlayout.widget.ConstraintLayout>

Question 12

Question

Insert the new contents in the following resources and demonstrate their uses in the android application Android Resources: (Color, Theme, String, Drawable, Dimension, Image).

MainActivity.java 
package com.example.resourcedemo; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:padding="@dimen/padding" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 

   <TextView 
       android:text="@string/welcome_text" 
       android:textSize="@dimen/text_size" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

   <ImageView 
       android:src="@drawable/sample_image" 
       android:layout_width="@dimen/image_size" 
       android:layout_height="@dimen/image_size" 
       android:layout_marginTop="20dp"/> 

   <Button 
       android:text="@string/button_text" 
       android:textColor="@color/white" 
       android:background="@drawable/button_bg" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="20dp"/> 

</LinearLayout> 

Strings.xml 

<resources> 
   <string name="app_name">ResourceDemo</string> 
   <string name="welcome_text">Welcome to Resource Demo</string> 
   <string name="button_text">Submit</string> 
</resources> 

Colors.xml 

<resources> 
   <color name="bg_color">#F0F0F0</color> 
   <color name="primary_color">#6200EE</color> 
   <color name="white">#FFFFFF</color> 
</resources> 

Button_bg.xml 
<shape xmlns:android="http://schemas.android.com/apk/res/android"> 
   <solid android:color="@color/primary_color"/> 
   <corners android:radius="12dp"/> 
</shape>

Dimens.xml 
<resources> 
   <dimen name="padding">20dp</dimen> 
   <dimen name="text_size">20sp</dimen> 
   <dimen name="image_size">150dp</dimen> 
</resources> 

Themes.xml 
<resources xmlns:tools="http://schemas.android.com/tools"> 
   <!-- Base application theme. --> 
   <style name="Theme.ResourceDemo" parent="Theme.Material3.DayNight.NoActionBar"> 
       <item name="android:windowBackground">@color/bg_color</item> 
   </style> 
</resources>

Question 13

Question

Define the following string resources in the strings.xml file for the registration form: Full Name, Email Password Confirm Password and Submit Use these string resources in the corresponding TextView and Button in your layout XML. Project Name: RegistrationForm

MainActivity.java 
package com.example.registrationform; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
} 

Strings.xml 
<resources> 
   <string name="app_name">RegistrationForm</string> 
   <string name="full_name">Full Name</string> 
   <string name="email">Email</string> 
   <string name="password">Password</string> 
   <string name="confirm_password">Confirm Password</string> 
   <string name="submit">Submit</string> 
</resources> 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:padding="20dp" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 

   <TextView 
       android:text="@string/full_name" 
       android:textSize="18sp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/full_name" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <TextView 
       android:text="@string/email" 
       android:textSize="18sp" 
       android:layout_marginTop="10dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/email" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <TextView 
       android:text="@string/password" 
       android:textSize="18sp" 
       android:layout_marginTop="10dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/password" 
       android:inputType="textPassword" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <TextView 
       android:text="@string/confirm_password" 
       android:textSize="18sp" 
       android:layout_marginTop="10dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/confirm_password" 
       android:inputType="textPassword" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <Button 
       android:text="@string/submit" 
       android:layout_marginTop="20dp" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

</LinearLayout>

Question 14

Question

Create a registration form where the form fields (Name, Email, Password, Confirm Password) are stacked vertically. Include a Submit button at the bottom of the form. Project Name: RegistrationForm

 
MainActivity.java
package com.example.registrationform; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
} 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:padding="24dp" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 

   <EditText 
       android:hint="@string/full_name" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/email" 
       android:inputType="textEmailAddress" 
       android:layout_marginTop="12dp" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/password" 
       android:inputType="textPassword" 
       android:layout_marginTop="12dp" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <EditText 
       android:hint="@string/confirm_password" 
       android:inputType="textPassword" 
       android:layout_marginTop="12dp" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

   <Button 
       android:text="@string/submit" 
       android:layout_marginTop="20dp" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"/> 

</LinearLayout> 

Strings.xml 
<resources> 
   <string name="app_name">RegistrationForm</string> 
   <string name="full_name">Full Name</string> 
   <string name="email">Email</string> 
   <string name="password">Password</string> 
   <string name="confirm_password">Confirm Password</string> 
   <string name="submit">Submit</string> 
</resources>

Question 15

Question

Create an android application, with one button and image view also set the background image in the application, the image should be changed on each click of the button (Use two images). Project Name: ImageSwitcherApp

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:gravity="center" 
   android:background="@drawable/bg_image" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 

   <ImageView 
       android:id="@+id/imageView" 
       android:src="@drawable/image1" 
       android:layout_width="200dp" 
       android:layout_height="200dp"/> 

   <Button 
       android:id="@+id/button" 
       android:text="Change Image" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

</LinearLayout> 

MainActivity.java 
package com.example.imageswitcherapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.Button; 
import android.widget.ImageView; 
public class MainActivity extends AppCompatActivity { 
   ImageView imageView; 
   Button button; 
   boolean isFirstImage = true; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       imageView = findViewById(R.id.imageView); 
       button = findViewById(R.id.button); 
       button.setOnClickListener(v -> { 
           if(isFirstImage){ 
               imageView.setImageResource(R.drawable.image2);
               isFirstImage = false; 
           } 
           else{ 
               imageView.setImageResource(R.drawable.image1); 
               isFirstImage = true; 
           }
       }); 
   } 
}

Question 16

Question

Create an android application to demonstrate the use of sub menu the toast should be appeared by selecting the sub menu item.

 
menu_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<menu xmlns:android="http://schemas.android.com/apk/res/android"> 
   <item 
       android:id="@+id/menu_options" 
       android:title="Options"> 
       <menu> 
           <item 
               android:id="@+id/sub_item1" 
               android:title="Profile"/> 
           <item 
               android:id="@+id/sub_item2" 
               android:title="Settings"/> 
           <item 
               android:id="@+id/sub_item3" 
               android:title="Logout"/> 
       </menu> 
   </item> 
</menu> 

MainActivity.java 
package com.example.submenudemo; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.Toast; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
   @Override 
   public boolean onCreateOptionsMenu(Menu menu) { 
       getMenuInflater().inflate(R.menu.menu_main, menu); 
       return true; 
   } 
   @Override 
   public boolean onOptionsItemSelected(MenuItem item) { 
       int id = item.getItemId(); 
       if(id == R.id.sub_item1){ 
           Toast.makeText(this, "Profile Selected", Toast.LENGTH_SHORT).show(); 
           return true; 
       } 
       else if(id == R.id.sub_item2){ 
           Toast.makeText(this, "Settings Selected", Toast.LENGTH_SHORT).show(); 
           return true; 
       } 
       else if(id == R.id.sub_item3){ 
           Toast.makeText(this, "Logout Selected", Toast.LENGTH_SHORT).show(); 
           return true; 
       } 
       return super.onOptionsItemSelected(item); 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:gravity="center" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
</LinearLayout> 

themes.xml 
<resources xmlns:tools="http://schemas.android.com/tools"> 
   <!-- Base application theme. --> 
   <style name="Base.Theme.SubMenuDemo" parent="Theme.Material3.DayNight"> 
       <!-- Customize your light theme here. --> 
       <!-- <item name="colorPrimary">@color/my_light_primary</item> --> 
   </style> 

   <style name="Theme.SubMenuDemo" parent="Base.Theme.SubMenuDemo" /> 
</resources>

Question 17

Question

Design a form with a RadioGroup for selecting the gender (Male/Female/Other). Include a Submit button that shows the selected gender in a TextView.

MainActivity.java 
package com.example.radiogroup; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.Button; 
import android.widget.RadioGroup; 
import android.widget.TextView; 
public class MainActivity extends AppCompatActivity { 
   RadioGroup radioGroup; 
   Button buttonSubmit; 
   TextView textViewResult; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       radioGroup = findViewById(R.id.radioGroup); 
       buttonSubmit = findViewById(R.id.buttonSubmit); 
       textViewResult = findViewById(R.id.textViewResult); 
       buttonSubmit.setOnClickListener(v -> { 
           int selectedId = radioGroup.getCheckedRadioButtonId(); 
           if(selectedId == -1){ 
               textViewResult.setText("Please select a gender"); 
           } 
           else{ 
               if(selectedId == R.id.radioMale){ 
                   textViewResult.setText("Selected Gender: Male"); 
               } 
               else if(selectedId == R.id.radioFemale){ 
                   textViewResult.setText("Selected Gender: Female"); 
               } 
               else{ 
                   textViewResult.setText("Selected Gender: Other"); 
               } 
           } 
       }); 
   } 
} 

strings.xml 
<resources> 
   <string name="app_name">GenderForm</string> 
   <string name="select_gender">Select Gender</string> 
   <string name="male">Male</string> 
   <string name="female">Female</string> 
   <string name="other">Other</string> 
   <string name="submit">Submit</string> 
</resources> 

activity.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:padding="20dp" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <TextView 
       android:text="@string/select_gender" 
       android:textSize="18sp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
   <RadioGroup 
       android:id="@+id/radioGroup" 
       android:layout_marginTop="10dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"> 
       <RadioButton 
           android:id="@+id/radioMale" 
           android:text="@string/male" 
           android:layout_width="wrap_content" 
           android:layout_height="wrap_content"/> 
       <RadioButton 
           android:id="@+id/radioFemale" 
           android:text="@string/female" 
           android:layout_width="wrap_content" 
           android:layout_height="wrap_content"/> 
       <RadioButton 
           android:id="@+id/radioOther" 
           android:text="@string/other" 
           android:layout_width="wrap_content" 
           android:layout_height="wrap_content"/> 
   </RadioGroup> 
   <Button 
       android:id="@+id/buttonSubmit" 
       android:text="@string/submit" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
   <TextView 
       android:id="@+id/textViewResult" 
       android:textSize="18sp" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
</LinearLayout>

Question 18

Question

Create a RelativeLayout for a profile screen with:A Profile Image centered at the top of the screen. A TextView displaying the name below the profile image, aligned to the center. A Button below the name, aligned to the center.

 
string.xml 
<resources> 
   <string name="app_name">ProfileScreen</string> 
   <string name="user_name">IVNO</string> 
   <string name="follow">Follow</string> 
</resources> 

MainActivity.java 
package com.example.profilescreen; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:padding="20dp"> 
   <!-- Profile Image --> 
   <ImageView 
       android:id="@+id/profileImage" 
       android:src="@drawable/profile_image" 
       android:layout_width="150dp" 
       android:layout_height="150dp" 
       android:layout_centerHorizontal="true" 
       android:layout_alignParentTop="true"/> 
   <!-- Name TextView --> 
   <TextView 
       android:id="@+id/textName" 
       android:text="@string/user_name" 
       android:textSize="22sp" 
       android:layout_below="@id/profileImage" 
       android:layout_centerHorizontal="true" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
   <!-- Button --> 
   <Button 
       android:id="@+id/buttonFollow" 
       android:text="@string/follow" 
       android:layout_below="@id/textName" 
       android:layout_centerHorizontal="true" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 

</RelativeLayout>

Question 19

Question

Write a program that logs the different lifecycle methods of an Activity (e.g., onCreate(), onStart(), onResume(), onPause(), onStop(), onDestroy()) to the logout.

 
MainActivity.java 
package com.example.activitylifecycledemo; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
public class MainActivity extends AppCompatActivity { 
   private static final String TAG = "LifecycleDemo"; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       Log.d(TAG, "onCreate() called"); 
   } 
   @Override 
   protected void onStart() { 
       super.onStart(); 
       Log.d(TAG, "onStart() called"); 
   } 
   @Override 
   protected void onResume() { 
       super.onResume(); 
       Log.d(TAG, "onResume() called"); 
   } 
   @Override 
   protected void onPause() { 
       super.onPause(); 
       Log.d(TAG, "onPause() called"); 
   } 
   @Override 
   protected void onStop() { 
       super.onStop(); 
       Log.d(TAG, "onStop() called"); 
   } 
   @Override 
   protected void onDestroy() { 
       super.onDestroy(); 
       Log.d(TAG, "onDestroy() called"); 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:gravity="center" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <TextView 
       android:text="Check Logcat for Lifecycle Methods" 
       android:textSize="18sp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
</LinearLayout>

Question 20

Question

Design a ListView that displays a list of items. Each item should be a simple TextView with a string from an array of names. The list should be populated dynamically in your Activity.

 
MainActivity.java 
package com.example.listviewdemo; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
public class MainActivity extends AppCompatActivity { 
   ListView listView; 
   String[] names = { 
           " ", 
           "IVNESH", 
           "PARAKEET", 
           "NARESH", 
           "PRATHAM", 
           "RUHI", 
           "SHIVANI", 
           "RIYADHI", 
   }; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       listView = findViewById(R.id.listView); 
       ArrayAdapter<String> adapter = 
               new ArrayAdapter<>(this, 
                       android.R.layout.simple_list_item_1, 
                       names); 
       listView.setAdapter(adapter); 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<ListView xmlns:android="http://schemas.android.com/apk/res/android" 
   android:id="@+id/listView" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"/>

Question 21

Question

Create an Activity that hosts a Fragment. When a button in the Activity is clicked, pass a string value to the Fragment and display it in a TextView. res → layout → fragment_my.xml

  
fragment_my.xml 
<?xml version="1.0" encoding="utf-8"?> 
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:gravity="center"> 
   <TextView 
       android:id="@+id/textViewFragment" 
       android:text="Message will appear here" 
       android:textSize="20sp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
</FrameLayout> 

MyFragment.java 
package com.example.fragmentdatademo; 
import android.os.Bundle; 
import androidx.fragment.app.Fragment; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.TextView; 
public class MyFragment extends Fragment { 
   TextView textView; 
   @Override 
   public View onCreateView(LayoutInflater inflater, ViewGroup container, 
                            Bundle savedInstanceState) { 
       View view = inflater.inflate(R.layout.fragment_my, container, false); 
       textView = view.findViewById(R.id.textViewFragment); 
       // Receive data from Activity 
       if(getArguments() != null){ 
           String message = getArguments().getString("data"); 
           textView.setText(message); 
       } 
       return view; 
   } 
} 

activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:padding="20dp" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <FrameLayout 
       android:id="@+id/fragmentContainer" 
       android:layout_width="match_parent" 
       android:layout_height="460dp" 
       android:layout_marginTop="20dp"> 
   </FrameLayout> 
   <Button 
       android:id="@+id/buttonSend" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Send Data to Fragment" /> 
</LinearLayout> 

MainActivity.java 
package com.example.fragmentdatademo; 
import androidx.appcompat.app.AppCompatActivity; 
import androidx.fragment.app.FragmentManager; 
import androidx.fragment.app.FragmentTransaction; 
import android.os.Bundle; 
import android.widget.Button; 
public class MainActivity extends AppCompatActivity { 
   Button buttonSend; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       buttonSend = findViewById(R.id.buttonSend); 
       buttonSend.setOnClickListener(v -> { 
           MyFragment fragment = new MyFragment(); 
           Bundle bundle = new Bundle(); 
           bundle.putString("data", "Hello from 4021,5059,5081!"); 
           fragment.setArguments(bundle); 
           FragmentManager fm = getSupportFragmentManager(); 
           FragmentTransaction ft = fm.beginTransaction(); 
           ft.replace(R.id.fragmentContainer, fragment); 
           ft.commit(); 
       }); 
   } 
}

Question 22

Question

Create an android application using linear layout and insert 10 animals in the list view and display the appropriate Toast. Project Name: AnimalListApp

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:orientation="vertical" 
   android:padding="10dp" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <ListView 
       android:id="@+id/listViewAnimals" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent"/> 
</LinearLayout> 

Mainactivity.java 
package com.example.animallistapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.ArrayAdapter; 
import android.widget.ListView; 
import android.widget.Toast; 
import android.widget.AdapterView; 
public class MainActivity extends AppCompatActivity { 
   ListView listView; 
   String[] animals = { 
           "Lion", 
           "Tiger", 
           "Elephant", 
           "Dog", 
           "Cat", 
           "Horse", 
           "Monkey", 
           "Zebra", 
           "Bear", 
           "Deer" 
   }; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       listView = findViewById(R.id.listViewAnimals); 
       ArrayAdapter<String> adapter = 
               new ArrayAdapter<>(this, 
                       android.R.layout.simple_list_item_1, 
                       animals); 
       listView.setAdapter(adapter); 
       // Display Toast on item click 
       listView.setOnItemClickListener((parent, view, position, id) -> { 
           String selectedAnimal = animals[position]; 
           Toast.makeText( 
                   MainActivity.this, 
                   "Selected: " + selectedAnimal, 
                   Toast.LENGTH_SHORT 
           ).show(); 
       }); 
   } 
}

Question 23

Question

Create an app that displays an ImageView. When the user clicks the ImageView, show a Toast with the message & Image clicked! Project Name : ImageClickApp Add one image “sample_image.png” app-> res->drawable

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:gravity="center" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <ImageView 
       android:id="@+id/imageView" 
       android:src="@drawable/sample_image" 
       android:layout_width="200dp" 
       android:layout_height="200dp" 
       android:clickable="true"/> 
</LinearLayout> 

Mainactivity.java 
package com.example.imageclickapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.widget.ImageView; 
import android.widget.Toast; 
public class MainActivity extends AppCompatActivity { 
   ImageView imageView; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       imageView = findViewById(R.id.imageView); 
       imageView.setOnClickListener(v -> { 
           Toast.makeText( 
                   MainActivity.this, 
                   "Image clicked!", 
                   Toast.LENGTH_SHORT 
           ).show(); 
       }); }}

Question 24

Question

Create the background service android application to play the ringtone/music. Project name: MusicServiceApp Inside app-> res Create a new folder “raw” Paste any audio inside raw folder “music.mp3” Create a java class -> “MusicService”

MusicService.java 
package com.example.musicserviceapp; 
import android.app.Service; 
import android.content.Intent; 
import android.media.MediaPlayer; 
import android.os.IBinder; 
public class MusicService extends Service { 
   MediaPlayer mediaPlayer; 
   @Override 
   public void onCreate() { 
       super.onCreate(); 
       mediaPlayer = MediaPlayer.create(this, R.raw.music); 
       mediaPlayer.setLooping(true); // plays continuously 
   } 
   @Override 
   public int onStartCommand(Intent intent, int flags, int startId) { 
       mediaPlayer.start(); // start music 
       return START_STICKY; // keeps service running 
   } 
   @Override 
   public void onDestroy() { 
       super.onDestroy(); 
       mediaPlayer.stop(); 
       mediaPlayer.release(); 
   } 
   @Override 
   public IBinder onBind(Intent intent) { 
       return null; 
   } 
} 

MainActivity.java 
package com.example.musicserviceapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.widget.Button; 
public class MainActivity extends AppCompatActivity { 
   Button startBtn, stopBtn; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       startBtn = findViewById(R.id.buttonStart); 
       stopBtn = findViewById(R.id.buttonStop); 
       startBtn.setOnClickListener(v -> { 
           startService(new Intent(MainActivity.this, MusicService.class)); 
       }); 
       stopBtn.setOnClickListener(v -> { 
           stopService(new Intent(MainActivity.this, MusicService.class)); 
       }); 
   } 
} 
             
Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:gravity="center" 
   android:orientation="vertical" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <Button 
       android:id="@+id/buttonStart" 
       android:text="Start Music" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
   <Button 
       android:id="@+id/buttonStop" 
       android:text="Stop Music" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
</LinearLayout> 

AndroidManifest.xml 
<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:tools="http://schemas.android.com/tools"> 
   <application 
       android:allowBackup="true" 
       android:dataExtractionRules="@xml/data_extraction_rules" 
       android:fullBackupContent="@xml/backup_rules" 
       android:icon="@mipmap/ic_launcher" 
       android:label="@string/app_name" 
       android:roundIcon="@mipmap/ic_launcher_round" 
       android:supportsRtl="true" 
       android:theme="@style/Theme.MusicServiceApp"> 
       <service android:name=".MusicService"/> 
       <activity 
           android:name=".MainActivity" 
           android:exported="true"> 
           <intent-filter> 
               <action android:name="android.intent.action.MAIN" /> 
               <category android:name="android.intent.category.LAUNCHER" /> 
           </intent-filter> 
       </activity> 
   </application> 
</manifest>

Question 25

Question

Design a simple login form using ConstraintLayout that has: Username and Password fields aligned vertically. Login button centered horizontally below the fields. Forgot Password? link aligned to the right of the password field. Task: Position all the elements using constraints in the ConstraintLayout.

 
Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<androidx.constraintlayout.widget.ConstraintLayout 
   xmlns:android="http://schemas.android.com/apk/res/android" 
   xmlns:app="http://schemas.android.com/apk/res-auto" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent" 
   android:padding="24dp"> 
   <!-- Username Field --> 
   <EditText 
       android:id="@+id/editUsername" 
       android:hint="@string/username" 
       android:layout_width="0dp" 
       android:layout_height="wrap_content" 
       app:layout_constraintTop_toTopOf="parent" 
       app:layout_constraintStart_toStartOf="parent" 
       app:layout_constraintEnd_toEndOf="parent"/> 
   <!-- Password Field --> 
   <EditText 
       android:id="@+id/editPassword" 
       android:hint="@string/password" 
       android:inputType="textPassword" 
       android:layout_width="0dp" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="16dp" 
       app:layout_constraintTop_toBottomOf="@id/editUsername" 
       app:layout_constraintStart_toStartOf="parent" 
       app:layout_constraintEnd_toEndOf="parent"/> 
   <!-- Forgot Password Link --> 
   <TextView 
       android:id="@+id/textForgot" 
       android:text="@string/forgot_password" 
       android:textColor="@android:color/holo_blue_dark" 
       android:layout_marginTop="8dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       app:layout_constraintTop_toBottomOf="@id/editPassword" 
       app:layout_constraintEnd_toEndOf="@id/editPassword"/> 
   <!-- Login Button --> 
   <Button 
       android:id="@+id/buttonLogin" 
       android:text="@string/login"
       android:layout_marginTop="24dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       app:layout_constraintTop_toBottomOf="@id/textForgot" 
       app:layout_constraintStart_toStartOf="parent" 
       app:layout_constraintEnd_toEndOf="parent"/> 
</androidx.constraintlayout.widget.ConstraintLayout> 

MainActivity.java 
package com.example.loginformapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
} 

Strings.xml 
<resources> 
   <string name="app_name">LoginFormApp</string> 
   <string name="username">Username</string> 
   <string name="password">Password</string> 
   <string name="login">Login</string> 
   <string name="forgot_password">Forgot Password?</string> 
</resources>

Question 26

Question

Create an android application to demonstrate the use of sub menu the toast should be appeared by selecting the sub menu item Name: SubMenuApp

In res → values → themes.xml 
Make sure this line is correct 
<style name="Base.Theme.SubMenuApp" parent="Theme.Material3.DayNight"> 
</style> 

Inside res folder create a menu folder 
Inside menu-> menu_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<menu xmlns:android="http://schemas.android.com/apk/res/android"> 
   <item 
       android:id="@+id/menu_more" 
       android:title="More Options"> 
       <menu> 
           <item 
               android:id="@+id/profile" 
               android:title="Profile"/> 
           <item 
               android:id="@+id/settings" 
               android:title="Settings"/> 
           <item 
               android:id="@+id/logout" 
               android:title="Logout"/> 
       </menu> 
   </item> 
</menu> 

Activity_main.xml 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:gravity="center" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
</LinearLayout> 

MainActivity.java 
package com.example.submenuapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.Toast; 
public class MainActivity extends AppCompatActivity { 
   // Create Menu 
   @Override 
   public boolean onCreateOptionsMenu(Menu menu) { 
       getMenuInflater().inflate(R.menu.menu_main, menu); 
       return true; 
   } 
   // Handle Sub Menu Click 
   @Override 
   public boolean onOptionsItemSelected(MenuItem item) { 
       int id = item.getItemId(); 
       if(id == R.id.profile){ 
           Toast.makeText(this, "Profile Selected", Toast.LENGTH_SHORT).show(); 
       } 
       else if(id == R.id.settings){ 
           Toast.makeText(this, "Settings Selected", Toast.LENGTH_SHORT).show(); 
       } 
       else if(id == R.id.logout){ 
           Toast.makeText(this, "Logout Selected", Toast.LENGTH_SHORT).show(); 
       } 
       return super.onOptionsItemSelected(item); 
   } 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
}

Question 27

Question

Design a screen with two buttons: Start and Stop. When the Start button is clicked, start a Timer (display the time in seconds). When the Stop button is clicked, stop the timer.

             
MainActivity.java 
package com.example.timerapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
import android.os.Handler; 
import android.widget.Button; 
import android.widget.TextView; 
public class MainActivity extends AppCompatActivity { 
   TextView textTimer; 
   Button startBtn, stopBtn; 
   Handler handler = new Handler(); 
   int seconds = 0; 
   boolean running = false; 
   Runnable runnable = new Runnable() { 
       @Override 
       public void run() { 
           if(running){ 
               seconds++; 
               textTimer.setText(String.valueOf(seconds)); 
               handler.postDelayed(this, 1000); // repeat every 1 sec 
           } 
       } 
   }; 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
       textTimer = findViewById(R.id.textTimer); 
       startBtn = findViewById(R.id.buttonStart); 
       stopBtn = findViewById(R.id.buttonStop); 
       startBtn.setOnClickListener(v -> { 
           if(!running){ 
               running = true; 
               handler.post(runnable); 
           } 
       }); 
       stopBtn.setOnClickListener(v -> running = false); 
   } 
} 

activity_main 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
   android:gravity="center" 
   android:orientation="vertical" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <!-- Timer Display --> 
   <TextView 
       android:id="@+id/textTimer" 
       android:text="0" 
       android:textSize="40sp" 
       android:layout_marginBottom="30dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
   <!-- Start Button --> 
   <Button 
       android:id="@+id/buttonStart" 
       android:text="Start" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
   <!-- Stop Button --> 
   <Button 
       android:id="@+id/buttonStop" 
       android:text="Stop" 
       android:layout_marginTop="20dp" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"/> 
</LinearLayout>

Question 28

Question

Create a simple Registration Form with the following fields: Name (Text Input) Email (Text Input) Phone Number (Text Input) Password (Password Input) Confirm Password (Password Input) Submit Button activity_main

<?xml version="1.0" encoding="utf-8"?> 
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android" 
   android:layout_width="match_parent" 
   android:layout_height="match_parent"> 
   <LinearLayout 
       android:orientation="vertical" 
       android:padding="24dp" 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content"> 
       <!-- Name --> 
       <EditText 
           android:hint="@string/name" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content"/> 
       <!-- Email --> 
       <EditText 
           android:hint="@string/email" 
           android:inputType="textEmailAddress" 
           android:layout_marginTop="12dp" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content"/> 
       <!-- Phone --> 
       <EditText 
           android:hint="@string/phone" 
           android:inputType="phone" 
           android:layout_marginTop="12dp" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content"/> 
       <!-- Password --> 
       <EditText 
           android:hint="@string/password" 
           android:inputType="textPassword" 
           android:layout_marginTop="12dp" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content"/> 
       <!-- Confirm Password --> 
       <EditText 
           android:hint="@string/confirm_password" 
           android:inputType="textPassword" 
           android:layout_marginTop="12dp" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content"/> 
       <!-- Submit Button --> 
       <Button 
           android:text="@string/submit" 
           android:layout_marginTop="20dp" 
           android:layout_width="match_parent" 
           android:layout_height="wrap_content"/> 
   </LinearLayout> 
</ScrollView> 

strings.xml 
<resources> 
   <string name="app_name">RegistrationFormApp</string> 
   <string name="name">Name</string> 
   <string name="email">Email</string> 
   <string name="phone">Phone Number</string> 
   <string name="password">Password</string> 
   <string name="confirm_password">Confirm Password</string> 
   <string name="submit">Submit</string> 
</resources> 

MainActivity.java 
package com.example.registrationformapp; 
import androidx.appcompat.app.AppCompatActivity; 
import android.os.Bundle; 
public class MainActivity extends AppCompatActivity { 
   @Override 
   protected void onCreate(Bundle savedInstanceState) { 
       super.onCreate(savedInstanceState); 
       setContentView(R.layout.activity_main); 
   } 
}