Switch in Android

A Switch is a widget used in Android applications to perform two-state operations, such as turning something on or off. It allows users to toggle settings between on and off with a simple switch. In this article, we will learn how to implement a Switch in Android. This Android article covered in both Java and Kotlin languages. 

Step by Step Implementation

Step 1: Creating a new project in Android Studio

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio.

Step 2: Adding Switch code in activity_main.xml file

In this file, we will use the LinearLayout and two switches inside it. Set the attributes of each switch like switch id, text etc. 

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:background="@color/white"
    android:orientation="vertical">

    <androidx.appcompat.widget.SwitchCompat
        android:id="@+id/switch1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Switch1"/>

    <androidx.appcompat.widget.SwitchCompat
        android:id="@+id/switch2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Switch2"/>
</LinearLayout>

Design UI:

Step 3: Accessing the Switch widget in MainActivity.kt file

Here, we will access the switches by using their respective ids and set onClickListener and Toast message if a switch is checked(ON) state. 
First of all, declare a variable to get the switch using it's id. 

val switch: SwitchCompat = findViewById(R.id.switch)

Note: We will be using SwitchCompat in this article. You can also choose to use SwitchMaterial.

then, set OnClick listener on the switch and use if condition to check the state of the button. 

switch.setOnCheckedChangeListener({ _ , isChecked ->
    val message = if (isChecked) "Switch:ON" else "Switch:OFF"
    Toast.makeText(this, message,Toast.LENGTH_SHORT).show()
})

Repeat the process for another switch in the MainActivity file.

MainActivity File:

package org.geeksforgeeks.demo;

import android.os.Bundle;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.SwitchCompat;

public class MainActivity extends AppCompatActivity {

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

        SwitchCompat switch1 = findViewById(R.id.switch1);
        switch1.setOnCheckedChangeListener((buttonView, isChecked) -> {
            String message = isChecked ? "Switch1:ON" : "Switch1:OFF";
            Toast.makeText(MainActivity.this, message, Toast.LENGTH_SHORT).show();
        });

        SwitchCompat switch2 = findViewById(R.id.switch2);
        switch2.setOnCheckedChangeListener((buttonView, isChecked) -> {
            String message = isChecked ? "Switch2:ON" : "Switch2:OFF";
            Toast.makeText(MainActivity.this, message, Toast.LENGTH_SHORT).show();
        });
    }
}

package org.geeksforgeeks.demo

import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.SwitchCompat

class MainActivity : AppCompatActivity() 
{
    override fun onCreate(savedInstanceState: Bundle?) 
    {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val switch1: SwitchCompat = findViewById(R.id.switch1)
        switch1.setOnCheckedChangeListener { _, isChecked ->
            val message = if (isChecked) "Switch1:ON" else "Switch1:OFF"
            Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
        }

        val switch2: SwitchCompat = findViewById(R.id.switch2)
        switch2.setOnCheckedChangeListener { _, isChecked ->
            val message = if (isChecked) "Switch2:ON" else "Switch2:OFF"
            Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
        }
    }
}

Output:

Here, two switches are shown in the emulator when we run the above code. We can change the state of the switches independently.