Play an Audio File in on Button Click Android Appliction

package com.example.lucifer.myapplication;
import android.app.Activity;
import android.content.res.AssetFileDescriptor;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import java.io.IOException;
public class MainActivity extends Activity
{
    public Button b;@
    Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final MediaPlayer mp = new MediaPlayer();
        Button b = (Button) findViewById(R.id.button_sound);
        b.setOnClickListener(new View.OnClickListener()
        {@
            Override
            public void onClick(View v)
            {
                if (mp.isPlaying())
                {
                    mp.stop();
                }
                try
                {
                    mp.reset();
                    AssetFileDescriptor afd;
                    afd = getAssets().openFd("myaudio.mp3");
                    mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
                    mp.prepare();
                    mp.start();
                }
                catch (IllegalStateException e)
                {
                    e.printStackTrace();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        });
    }
}
"activity_main.xml"
file - < LinearLayout xmlns: android = "http://schemas.android.com/apk/res/android"
android: id = "@+id/layout_login"
android: layout_width = "fill_parent"
android: layout_height = "wrap_content"
android: orientation = "vertical"
android: layout_gravity = "top" > < Button
android: id = "@+id/button_sound"
android: layout_gravity = "center"
android: layout_width = "wrap_content"
android: layout_height = "wrap_content"
android: layout_marginLeft = "150dp"
android: text = "Click me for sound" / > < /LinearLayout>