How to Implement OnSavedInstanceState in Android?

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

 <LinearLayout      

xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:gravity="center_horizontal"

android:orientation="vertical"

android:padding="16dp"

tools:context=".MainActivity">

  <TextView

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:textAlignment="center"

android:textSize="22sp"

android:text="Candidroot solutions"/>

   <EditText

     android:id="@+id/edit_text"

     android:layout_marginTop="10dp"

     android:layout_width="match_parent"

     android:layout_height="wrap_content"

     android:background="@android:drawable/editbox_background"

     android:hint="Enter text"

     android:padding="12dp" />

    <RadioGroup

     android:id="@+id/radio_group"

     android:layout_width="wrap_content"

     android:layout_height="wrap_content"

     android:layout_marginTop="16dp"

     android:orientation="horizontal">

     <RadioButton

         android:id="@+id/rb_true"

         android:layout_width="wrap_content"

         android:layout_height="wrap_content"

         android:padding="12dp"

         android:text="Male"

         android:textSize="24sp" />

      <RadioButton

         android:id="@+id/rb_false"

         android:layout_width="wrap_content"

         android:layout_height="wrap_content"

         android:padding="12dp"

         android:text="Female"

         android:textSize="24sp" />

 </RadioGroup>

 </LinearLayout>

 import android.os.Bundle;

 import android.text.Editable;

 import android.text.TextWatcher;

 import android.widget.EditText;

 import android.widget.RadioGroup;

 import android.widget.Toast;

 import androidx.annotation.NonNull;

 import androidx.appcompat.app.AppCompatActivity;

 public class MainActivity extends AppCompatActivity {

// initialize variables

private EditText editText;

private RadioGroup radioGroup;

private String string;

private boolean testBoolean;

private  int anInt;

 @Override

 protected void onCreate(Bundle savedInstanceState) {

     super.onCreate(savedInstanceState);

     setContentView(R.layout.activity_main);

     // assign variables

     editText = findViewById(R.id.edit_text);

     radioGroup = findViewById(R.id.radio_group);

     editText.addTextChangedListener(new TextWatcher() {

         @Override

         public void beforeTextChanged(CharSequence s, int start, int count, int after) {

         }

         @Override

         public void onTextChanged(CharSequence s, int start, int before, int count) {

             // get string value

             string = String.valueOf(s);

         }

         @Override

         public void afterTextChanged(Editable s) {

         }

     });

     radioGroup.setOnCheckedChangeListener((group, checkedId) -> {

         // get boolean value

         testBoolean = checkedId == R.id.rb_true;

     });

}

  @Override

  protected void onSaveInstanceState(@NonNull Bundle outState) {

     // put string value

     outState.putString("string_value", string);

     // put boolean value

     outState.putBoolean("boolean_value", testBoolean);

     // Put int value

     outState.putInt("int_value", anInt);

     super.onSaveInstanceState(outState);

}

 @Override

 protected void onRestoreInstanceState(@NonNull Bundle savedInstanceState) {

     string = savedInstanceState.getString("string_value");

     testBoolean = savedInstanceState.getBoolean("boolean_value");

     anInt = savedInstanceState.getInt("int_value");

     // display toast

     Toast.makeText(getApplicationContext(), string + " - " + testBoolean + " - " + anInt, Toast.LENGTH_SHORT).show();

     super.onRestoreInstanceState(savedInstanceState);

 }

 }