Wake the device up when app prompts user

Question

I\'m using handler to repeatedly prompt user for an input every e.g. 5 minutes. When the device goes into sleeping mode and screen is locked, how can I wake the device up wh

Answer 1

Normally wakelock doesnt actual turn on the screen. So you should get the wake lock with

ACQUIRE_CAUSES_WAKEUP

as an additional flag.

Answer 2

From what I see, you are releasing the wake lock immediately after acquiring it. That's why it gives the impression of not working. Remove it and put it somewhere else outside the method that acquires it.

mReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        Vibrator v = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
        v.vibrate(300);
        PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
        KeyguardManager km = (KeyguardManager) getSystemService(Context.KEYGUARD_SERVICE);
        WakeLock wl = null;

        if (!pm.isScreenOn()) {
            KeyguardLock kl = km.newKeyguardLock("TAG");
            kl.disableKeyguard();
            wl = pm.newWakeLock(
                PowerManager.SCREEN_BRIGHT_WAKE_LOCK | 
                PowerManager.ACQUIRE_CAUSES_WAKEUP, "TAG");
            wl.acquire();
        }

        Toast.makeText(context, "Alarm worked", Toast.LENGTH_LONG).show();
    }
};

Answer 3

Take a look for AlarmManager class http://developer.android.com/reference/android/app/AlarmManager.html It's something like "cron"

Ok, here is a piece of working code - first comes the activity class:

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.os.PowerManager;
import android.os.PowerManager.WakeLock;

public class MainActivity extends Activity {
    private WakeLock wl;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        //acquire wake lock
        PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
        wl = pm.newWakeLock(PowerManager.ACQUIRE_CAUSES_WAKEUP|PowerManager.SCREEN_BRIGHT_WAKE_LOCK, "TAG");
        wl.acquire();

        // schedule alarm
        Intent i = new Intent();
        i.setAction(WakeReciever.WAKE_INTENT);
        PendingIntent pIntent = PendingIntent.getBroadcast(this, 0, i, 0);

        AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
        am.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 120000,
                pIntent);
    }

    @Override
    protected void onPause() {
        wl.release();
        super.onPause();
    }

}

Next comes BroadcastReceiver:

package com.test;

import android.content.BroadcastReceiver;
import android.content.Intent;
import android.content.Context;
import android.os.PowerManager;
import android.os.PowerManager.WakeLock;

public class WakeReciever extends BroadcastReceiver {
    public static final String WAKE_INTENT = "com.test.WAKE"; 


    /**
     * @see android.content.BroadcastReceiver#onReceive(Context,Intent)
     */
    @Override
    public void onReceive(Context context, Intent intent) {
        //acquire wake lock

        PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
        WakeLock wl = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP, "TAG");
        wl.acquire();


        //start activity
        Intent i = new Intent();
        i.setClassName("com.test", "com.test.MainActivity");
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        context.startActivity(i);

        wl.release();
    }
}

And finally don't forget about the manifest file:

<?xml version="1.0" encoding="UTF-8"?>
<manifest android:versionCode="1" android:versionName="1.0"
    package="com.test" xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-sdk android:minSdkVersion="8"/>
    <uses-permission android:name="android.permission.WAKE_LOCK"></uses-permission>
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:label="@string/app_name" android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <receiver android:name=".WakeReciever" android:enabled="true">
            <intent-filter>
                <action android:name="com.test.WAKE"></action>
            </intent-filter>
        </receiver>

    </application>
</manifest>