RadioButton en Android

Ejercicio en Android Studio

En el telefono

Codigo

package com.example.myapplication; 

 import androidx.appcompat.app.AppCompatActivity;

 import android.os.Bundle; import android.view.View;

 import android.widget.RadioButton;

 import android.widget.Toast;

 public class MainActivity extends AppCompatActivity { 

 private RadioButton S1,S2,S3; 

 @Override 

protected void onCreate(Bundle savedInstanceState) { 

super.onCreate(savedInstanceState); 

 setContentView(R.layout.activity_main); 

 S1= (RadioButton) findViewById(R.id.radioButton); 

 S2= (RadioButton) findViewById(R.id.radioButton2);

 S3= (RadioButton) findViewById(R.id.radioButton3); 

 }

 public void seleccion(View view){

 if(S1.isChecked()==true){ Toast.makeText(this,"seleccion 1",Toast.LENGTH_LONG).show(); }else if(S2.isChecked()==true){ Toast.makeText(this,"seleccion 2",Toast.LENGTH_LONG).show(); }else if(S3.isChecked()==true){ Toast.makeText(this,"seleccion 3",Toast.LENGTH_LONG).show(); } } }