I will soon released a new version of my app to support to galaxy ace.
You can download here: https://play.google.com/store/apps/details?id=droid.pr.coolflashlightfree
In order to solve your problem you should do this:
this._camera = Camera.open();
this._camera.startPreview();
this._camera.autoFocus(new AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
}
});
Parameters params = this._camera.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_ON);
this._camera.setParameters(params);
params = this._camera.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_OFF);
this._camera.setParameters(params);
don't worry about FLASH_MODE_OFF because this will keep the light on, strange but it's true
to turn off the led just release the camera