radiobutton

<?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:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="app.com.example.android.image.MainActivity"
    android:orientation="vertical">

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:textColor="#000000"
        android:textSize="30dp"
        android:text="Siapa nama tokoh utama di Anime Naruto"/>

    <RadioGroup
        android:id="@+id/rbgrup"
        android:layout_marginTop="50dp"
        android:onClick="radiocheked"
        android:layout_gravity="center_horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <RadioButton
            android:id="@+id/naruto"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Naruto"/>
        <RadioButton
            android:id="@+id/sasuke"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Sasuke"/>
        <RadioButton
            android:id="@+id/sakura"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Sakura"/>
    </RadioGroup>
</LinearLayout>

package app.com.example.android.image;

import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    AlertDialog.Builder builder;
    RadioGroup rbgroup;

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

         rbgroup = (RadioGroup)findViewById(R.id.rbgrup);

    }

    public void radiocheked(View view) {

        Boolean checked = ((RadioButton) view).isChecked();

        switch (view.getId()) {
            case R.id.naruto:
                if (checked)
                    tampilDialog();
                break;

            case R.id.sasuke:
                if (checked)
                    jawabanSalah();
                break;
            case R.id.sakura:
                if (checked)
                    jawabanSalah();
                break;
        }

    }
    //menampilkan dialog jiga benar
    public void tampilDialog() {

        builder = new AlertDialog.Builder(this);
        builder.setCancelable(false);
        builder.setTitle("Selamat !!!");
        builder.setMessage("Jawaban anda benar : Naruto");
        builder.setPositiveButton("OKE", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                Toast.makeText(MainActivity.this, "Selamat", Toast.LENGTH_SHORT).show();
            }
        });

        builder.setNegativeButton("ULANGI", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {
                rbgroup.clearCheck();
            }
        });

        builder.create().show();

    }
    //menampilkan toast text ketika jawaban salah
    public void jawabanSalah(){

        Toast.makeText(this, "Jawaban anda Salah", Toast.LENGTH_SHORT).show();

    }
}