Turn off screen programmatically when face is close the screen on Android

I found solution by disassembling one very famous VoIP application. This activity after pressing button1 will disable screen and hardware keys when you close sensors. After pressing button2 this function will be switched off.

Also, this function required permission:

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

Activity. Try it.

public class MainActivity extends Activity {

    private Button button1;
    private Button button2;
    private PowerManager powerManager;
    private PowerManager.WakeLock wakeLock;
    private int field = 0x00000020;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        try {
            // Yeah, this is hidden field.
            field = PowerManager.class.getClass().getField("PROXIMITY_SCREEN_OFF_WAKE_LOCK").getInt(null);
        } catch (Throwable ignored) {
        }

        powerManager = (PowerManager) getSystemService(POWER_SERVICE);
        wakeLock = powerManager.newWakeLock(field, getLocalClassName());

        setContentView(R.layout.main);
        button1 = (Button) findViewById(R.id.button1);
        button2 = (Button) findViewById(R.id.button2);

        button1.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                if(!wakeLock.isHeld()) {
                    wakeLock.acquire();
                }
            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                if(wakeLock.isHeld()) {
                    wakeLock.release();
                }
            }
        });
    }
}