gc freed xxxx objects and than freeze application - garbage-collection

Question

I'm trying to create simple app which contains of ten activities. Each activity look pretty much the same, it has four buttons (different color) and when one particular button is clicked it's open next activity. OnCreate method of every activity has mediaplayer that play name of that activity. After some time I see in LogCat that gc freed some objects and at that time Activity don't play any sound and buttons are disabled.
Do you have any advice or suggestions how to resole that?
Here is code of one Activity:
public class Green extends Activity {
int buttonActive = 0;
int buttonWrong = 0;
MediaPlayer player;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_green);
buttonWrong = 0;
playSound();
Button btn = (Button)findViewById(R.id.button1);
Button btn2 = (Button)findViewById(R.id.button2);
Button btn3 = (Button)findViewById(R.id.button3);
Button btn4 = (Button)findViewById(R.id.button4);
btn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(buttonActive == 1){
playSoundCorrect();
Intent intent = new Intent(v.getContext(),Blue.class);
startActivity(intent);
}
}
});
btn2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if(buttonActive == 1 && buttonWrong == 0){
buttonWrong = 1;
playSoundWrong();
}
}
});
btn3.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if(buttonActive == 1 && buttonWrong == 0){
buttonWrong = 1;
playSoundWrong();
}
}
});
btn4.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if(buttonActive == 1 && buttonWrong == 0){
buttonWrong = 1;
playSoundWrong();
}
}
});
}
#Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
finish();
}
private void playSound(){
MediaPlayer player = MediaPlayer.create(this, R.raw.green);
player.start();
player.setOnCompletionListener(new OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer mp) {
mp.release();
buttonActive = 1;
}
});
}
private void playSoundWrong(){
player = MediaPlayer.create(this, R.raw.wrong2);
if(!player.isPlaying()){
player.start();
}
player.setOnCompletionListener(new OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer mp) {
mp.release();
buttonWrong = 0;
}
});
}
private void playSoundCorrect(){
MediaPlayer player = MediaPlayer.create(this, R.raw.correct);
player.start();
player.setOnCompletionListener(new OnCompletionListener() {
#Override
public void onCompletion(MediaPlayer mp) {
mp.release();
}
});
}
}

Answer 1

It looks like in private void playSound you're masking the class's player property. If you say player = MediaPlayer.create then the class's player property will be set to the new MediaPlayer, and the player will be reachable so long as the class is reachable. Instead you're saying MediaPlayer player = MediaPlayer.create, which is creating a new player variable that is scoped to the playSound method - once the method terminates the player is no longer reachable and will be garbage-collected, even if the class is still reachable.