Simple Android mp3 media player example

Here i want to write about my first experience in Android Dev.
This application just play embedded in application mp3 file. That’s all.
Below you can download the source code.
In first step i create a simple Android UI. Below you can see this:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
android:id="@+id/widget31"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
    <Button
        android:text="@string/play_str"
        android:textSize="15pt"
        android:textStyle="bold"
        android:id="@+id/ButtonPlayStop"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>
    <SeekBar
        android:id="@+id/SeekBar01"
        android:layout_height="wrap_content"
        android:layout_width="fill_parent"
        android:layout_below="@id/ButtonPlayStop"/>
</RelativeLayout>

In my simple mp3 media player i have few string constans, like “PLAY”, “PAUSE”, etc. The best practice is place this constats in special part of project. That part call values. In this part i Eclipse create for me strings.xml file and change it. Bellow you can see strings.xml content:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="app_name">Android mp3 player</string>
    <string name="play_str">PLAY</string>
    <string name="pause_str">PAUSE</string>
</resources>

It’s very simple and useful practice.

Next i make changes in Activity file (Mp3player.java). Bellow i give you some comments about it:

package com.hrupin.mp3player;

import com.hrupin.mp3player.R;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.SeekBar;

public class Mp3player extends Activity {

    private Button buttonPlayStop;
    private MediaPlayer mediaPlayer;
    private SeekBar seekBar;

    private final Handler handler = new Handler();

    // Here i override onCreate method.
    //
    // setContentView() method set the layout that you will see then
    // the application will starts
    //
    // initViews() method i create to init views components.
    @Override
    public void onCreate(Bundle icicle) {
            super.onCreate(icicle);
            setContentView(R.layout.main);
            initViews();  

    }

    // This method set the setOnClickListener and method for it (buttonClick())
    private void initViews() {
        buttonPlayStop = (Button) findViewById(R.id.ButtonPlayStop);
        buttonPlayStop.setOnClickListener(new OnClickListener() {@Override public void onClick(View v) {buttonClick();}});

        mediaPlayer = MediaPlayer.create(this, R.raw.testsong_20_sec); 

        seekBar = (SeekBar) findViewById(R.id.SeekBar01);
        seekBar.setMax(mediaPlayer.getDuration());
        seekBar.setOnTouchListener(new OnTouchListener() {@Override public boolean onTouch(View v, MotionEvent event) {
        	seekChange(v);
			return false; }
		});

    }

    public void startPlayProgressUpdater() {
    	seekBar.setProgress(mediaPlayer.getCurrentPosition());

		if (mediaPlayer.isPlaying()) {
			Runnable notification = new Runnable() {
		        public void run() {
		        	startPlayProgressUpdater();
				}
		    };
		    handler.postDelayed(notification,1000);
    	}else{
    		mediaPlayer.pause();
    		buttonPlayStop.setText(getString(R.string.play_str));
    		seekBar.setProgress(0);
    	}
    } 

    // This is event handler thumb moving event
    private void seekChange(View v){
    	if(mediaPlayer.isPlaying()){
	    	SeekBar sb = (SeekBar)v;
			mediaPlayer.seekTo(sb.getProgress());
		}
    }

    // This is event handler for buttonClick event
    private void buttonClick(){
        if (buttonPlayStop.getText() == getString(R.string.play_str)) {
            buttonPlayStop.setText(getString(R.string.pause_str));
            try{
            	mediaPlayer.start();
                startPlayProgressUpdater();
            }catch (IllegalStateException e) {
            	mediaPlayer.pause();
            }
        }else {
            buttonPlayStop.setText(getString(R.string.play_str));
            mediaPlayer.pause();
        }
    }
}