How do I keep the screen on in my App? [duplicate]

For my Android app I never want the phone to lock or the back light to turn off

Add one line of code after setContentView() in onCreate()

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_flag);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}

Lots of answers already exist here! I am answering this question with additional and reliable solutions:

Using PowerManager.WakeLock is not so reliable a solution, as the app requires additional permissions.

<uses-permission android:name="android.permission.WAKE_LOCK" />

Also, if it accidentally remains holding the wake lock, it can leave the screen on.

So, I recommend not using the PowerManager.WakeLock solution. Instead of this, use any of the following solutions:

First:

We can use getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); in onCreate()

@Override
        protected void onCreate(Bundle icicle) {
            super.onCreate(icicle);    
            getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        }

Second:

we can use keepScreenOn

1. implementation using setKeepScreenOn() in java code:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        View v = getLayoutInflater().inflate(R.layout.driver_home, null);// or any View (incase generated programmatically ) 
        v.setKeepScreenOn(true);
        setContentView(v);
       }

Docs http://developer.android.com/reference/android/view/View.html#setKeepScreenOn(boolean)

2. Adding keepScreenOn to xml layout

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:keepScreenOn="true" >

Docs http://developer.android.com/reference/android/view/View.html#attr_android%3akeepScreenOn

Notes (some useful points):

1. It doesn't matter that keepScreenOn should be used on a Main/Root/Parent View. It can be used with any child view and will work the same way it works in a parent view.
2. The only thing that matters is that the view's visibility must be visible. Otherwise, it will not work!

Use PowerManager.WakeLock class inorder to perform this. See the following code:

import android.os.PowerManager;

public class MyActivity extends Activity {

    protected PowerManager.WakeLock mWakeLock;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(final Bundle icicle) {
        setContentView(R.layout.main);

        /* This code together with the one in onDestroy() 
         * will make the screen be always on until this Activity gets destroyed. */
        final PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
        this.mWakeLock = pm.newWakeLock(PowerManager.SCREEN_DIM_WAKE_LOCK, "My Tag");
        this.mWakeLock.acquire();
    }

    @Override
    public void onDestroy() {
        this.mWakeLock.release();
        super.onDestroy();
    }
}

Use the follwing permission in manifest file :

<uses-permission android:name="android.permission.WAKE_LOCK" />

Hope this will solve your problem...:)