 XML code:-

<?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:gravity="center">

<TextView
android:id="@+id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@color/white"
android:text="Bluethoot"
android:textColor="@color/black"
android:textSize="30sp"
android:textStyle="bold|normal" />

<ToggleButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/tglbtn"
android:layout_toRightOf="@id/text1"
android:layout_marginLeft="20sp"
android:onClick="ToggleEvent"/>

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/status"
android:textColor="@color/blue"
android:layout_below="@id/text1"
android:layout_marginTop="30sp"
android:layout_marginLeft="50sp"
android:textSize="20sp"
android:text=""/>
</RelativeLayout>

 Colour XML code :-

<?xml version="1.0" encoding="utf-8"?>
<resources>
<color name="black">#FF000000</color>
<color name="white">#FFFFFFFF</color>
<color name="blue">#001289</color>
</resources>

 Java Code :-

package com.example.mad9;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.ToggleButton;

import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

public class MainActivity extends AppCompatActivity {

ToggleButton btn;
TextView status;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
EdgeToEdge.enable(this);
setContentView(R.layout.activity_main);
btn=findViewById(R.id.tglbtn);
status=findViewById(R.id.status);
}
public void ToggleEvent(View v){
if(btn.getText().toString().toLowerCase().equals("off")){
status.setText("It is OFF Now");
}else {
status.setText("It is On Now");
}
}
}
Output :-
2)

 XML code :-

<?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="20dp"
android:layout_marginTop="60dp">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="top|center"
android:text="calculator"
android:layout_marginLeft="130dp"
android:textSize="20dp"
android:layout_marginBottom="40dp">
</TextView>

<EditText
android:id="@+id/num1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Enter first number"
android:inputType="numberDecimal"
android:textSize="20sp"/>

<EditText
android:id="@+id/num2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="Enter second number"
android:inputType="numberDecimal"
android:textSize="20sp"/>

<Button
android:id="@+id/btnAdd"
android:backgroundTint="@color/blue"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Addition (+)" />

<Button
android:id="@+id/btnSubtract"
android:backgroundTint="@color/blue"
 android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Subtraction (-)" />

<Button
android:id="@+id/btnMultiply"
android:backgroundTint="@color/blue"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Multiplication (×)" />

<Button
android:id="@+id/btnDivide"
android:backgroundTint="@color/blue"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Division (÷)" />

<TextView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Result: "
android:textSize="20sp"
android:textStyle="bold"
android:padding="10dp" />

</LinearLayout>

 Colour XML code:-

<?xml version="1.0" encoding="utf-8"?>

<resources>
<color name="black">#FF000000</color>
<color name="white">#FFFFFFFF</color>
<color name="blue">#001289</color>
</resources>

 Java code :-
package com.example.mad9;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

EditText num1, num2;
Button btnAdd, btnSubtract, btnMultiply, btnDivide;
TextView result;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

num1 = findViewById(R.id.num1);
num2 = findViewById(R.id.num2);
btnAdd = findViewById(R.id.btnAdd);
btnSubtract = findViewById(R.id.btnSubtract);
btnMultiply = findViewById(R.id.btnMultiply);
btnDivide = findViewById(R.id.btnDivide);
result = findViewById(R.id.result);

btnAdd.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculate('+');
}
});

btnSubtract.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculate('-');
}
});

btnMultiply.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculate('*');
}
});
 btnDivide.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calculate('/');
}
});
}

private void calculate(char operator) {

String value1 = num1.getText().toString();
String value2 = num2.getText().toString();

if (value1.isEmpty() || value2.isEmpty()) {
Toast.makeText(this, "Please enter both numbers",
Toast.LENGTH_SHORT).show();
return;
}

double number1 = Double.parseDouble(value1);

double number2 = Double.parseDouble(value2);
double output = 0;

switch (operator) {
case '+':
output = number1 + number2;
break;
case '-':
output = number1 - number2;
break;
case '*':
output = number1 * number2;
break;
case '/':
if (number2 == 0) {
Toast.makeText(this, "Number cannot divide by 0",
Toast.LENGTH_SHORT).show();
return;
}
output = number1 / number2;
break;
}
result.setText("Result: " + output);
}
}

 OutPut :-