How to save state of RadioButton in android

Hello friend today we will learn about How to save state of RadioButton in android.Today we use switch in many ways in our app like to change dark mode or theme.

First we are create a new project in android studio or paste code where want to use this function.First of all we will create a project in android studio or where we want to use this method we will paste it there.

activity_main

<?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">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="10dp"
        android:text="RadioButton "
        android:textColor="@color/purple_500"
        android:textSize="20sp"
        android:textStyle="bold" />

    <RadioGroup
        android:id="@+id/radio_Group"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal">

        <RadioButton
            android:id="@+id/radioButton1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:text="Default" />


        <RadioButton
            android:id="@+id/radioButton2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:text="Night Mode" />

    </RadioGroup>

    <Button
        android:id="@+id/btn_summit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="Summit" />

</LinearLayout>

MainActivity

package com.example.darkmode;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    private RadioGroup radioGroup;
    private RadioButton radioButton1, radioButton2;
    private Button btn;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_radio_button);
        radioGroup = findViewById(R.id.radio_Group);
        radioButton1 = findViewById(R.id.radioButton1);
        radioButton2 = findViewById(R.id.radioButton2);
        btn = findViewById(R.id.btn_summit);
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        radioButton1.setChecked(sharedPreferences.getBoolean("btn1", false));
        radioButton2.setChecked(sharedPreferences.getBoolean("btn2", false));
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (radioButton1.isChecked()) {
                    editor.putBoolean("btn1", true);
                    editor.apply();
                    radioButton1.setChecked(true);
                    Toast.makeText(RadioActivity.this, "Radio button 1", Toast.LENGTH_SHORT).show();

                }
                else
                {
                    editor.putBoolean("btn1", false);
                    editor.apply();
                    radioButton1.setChecked(false);
                } if (radioButton2.isChecked()) {
                    editor.putBoolean("btn2", true);
                    editor.apply();
                    radioButton2.setChecked(true);
                    Toast.makeText(RadioActivity.this, "Radio button 2", Toast.LENGTH_SHORT).show();

                }

                else{
                    editor.putBoolean("btn2", false);
                    editor.apply();
                    radioButton2.setChecked(false);
                }
            }
        });

    }
}

Thanks ....