wake lock does not work [duplicate]

Question

This question already has answers here:

WakeLock not working (2 answers)

Closed 8 years ago.

I have posted this question before and no one could answer it so I am trying again as this issue makes my app worthless. I need the sound to keep playing when the screen times out or the user taps the power button. I have read almost every online post about wake locks that I can find and i can not get it to work. below is one of the .Java files that plays a sound based on the user selected input. Everything works great except that when the screen goes dark the sound stops playing. Just a note, I am very new to this so if this code is sloppy or redundant please let me know.

package com.androidsleepmachine.gamble;

import android.app.Activity;
import android.content.Context;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.PowerManager;
import android.view.KeyEvent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;

public class Ship extends Activity implements View.OnClickListener {
public static final Integer[] TIME_IN_MINUTES = { 30, 45, 60, 180, 360 };
public MediaPlayer mediaPlayer;
public Handler handler = new Handler();
public Button button2;
public Spinner spinner2;
public PowerManager.WakeLock wl;


// Initialize the activity
@Override
public void onCreate(Bundle savedInstanceState) {
    PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
    PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, 
"Playwhenoff");

    super.onCreate(savedInstanceState);
     wl.acquire();
    setContentView(R.layout.ship);
    button2 = (Button) findViewById(R.id.btn2);
    button2.setOnClickListener(this);
    spinner2 = (Spinner) findViewById(R.id.spinner2);
    ArrayAdapter<Integer> adapter = new ArrayAdapter<Integer>(this,
            android.R.layout.simple_spinner_item, TIME_IN_MINUTES);

adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner2.setAdapter(adapter);

}

// Play the sound and start the timer
private void playSound(int resourceId) {
    // Cleanup any previous sound files
    cleanup();
    // Create a new media player instance and start it

    mediaPlayer = MediaPlayer.create(this, resourceId);
    mediaPlayer.start();
    // Create the timer to stop the sound after x number of milliseconds
    int selectedTime = TIME_IN_MINUTES[spinner2.getSelectedItemPosition()];
    handler.postDelayed(runnable, selectedTime * 60 * 1000);
}

// Handle button callback
@Override
public void onClick(View v) {
    switch (v.getId()) {
    case R.id.btn2:
        playSound(R.raw.ocean_ship);
        break;
    }
}

protected void onStop() {

    cleanup();
    super.onStop();
}

// Stop the sound and cleanup the media player
public void cleanup() {
    if (mediaPlayer != null) {
        mediaPlayer.stop();
        mediaPlayer.release();
        mediaPlayer = null;
        wl.release();
    }
    // Cancel any previously running tasks
    handler.removeCallbacks(runnable);
}

// Runnable task used by the handler to stop the sound
public Runnable runnable = new Runnable() {
    public void run() {
        cleanup();
    }
};


@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    wl.release();
}

}

Answer 1

This probably has nothing to do with the WakeLock. Your activity is probably being called with onStop() when the screen turns off.

Audio players usually use a service for the audio playback, so the playback can run independently of UI concerns like this.

Answer 2

You are releasing your wakeLock onPause ->

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    wl.release(); // -> This is the line where you release the wakelock
}

When your device "goes to sleep", it goes like onPause -> onStop.

If you release your wakelock onPause, you will not be able to play your music with your screen off, because the system will not keep your CPU awaked.

Release it somewhere else (perhaps onDestroy?) and it should work.