onSensorChanged() is not called

I was not working with Sensors so far, but it looks like you have obtained SensorManager but did not register any listener for changes that should occur. Just ask yourself how could be onSensorChanged called?

Have a look at the sample on official android tutorial site about sensors and you could see this in onResume() method:

@Override
protected void onResume() {
    super.onResume();
    mSensorManager.registerListener(this, mLight, SensorManager.SENSOR_DELAY_NORMAL);
}

Also don't forget to study whole page it can help you a lot.

Edit:

I had to copy paste your sources because I haven't seen any problem. There are 2 basicaly:

• Toast is not appearing because you haven't told him to... Toast.show() will display it. But you rather use Log to output changes into console. It's up to you
• Do not retype float into int in onSensorChanged() method because all values are 0 or (1/-1 if you are lucky)

So result is following:

@Override
public void onSensorChanged(SensorEvent event) {
    float xValue = event.values[0];
    float yValue = event.values[1];
    float zValue = event.values[2];
    Log.d(LOG_TAG, "x:"+xValue +";y:"+yValue+";z:"+zValue);
}

other methods are correct