I always wonder the use of a flash light on a phone. This simple app is more useful than anything. So here is the code to build a flashlight app, MainActivity.java import android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.content.pm.PackageManager; import android.hardware.Camera; import android.hardware.Camera.Parameters; import android.media.MediaPlayer; import android.media.MediaPlayer.OnCompletionListener; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.ImageButton; public class MainActivity extends Activity { ImageButton btnSwitch; private Camera camera; private boolean isFlashOn; private boolean hasFlash; Parameters params; MediaPlayer mp; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // flash switch button ...