public void onClick(View view) {
    int currentNightMode = getResources().getConfiguration().uiMode
            & Configuration.UI_MODE_NIGHT_MASK;
    switch (currentNightMode) {
        case Configuration.UI_MODE_NIGHT_NO:
            // Night mode is not active, we're in day time
            Toast.makeText(getApplicationContext(), "Day Time", Toast.LENGTH_SHORT).show();
        case Configuration.UI_MODE_NIGHT_YES:
            // Night mode is active, we're at night!
            Toast.makeText(getApplicationContext(), "Night Time", Toast.LENGTH_SHORT).show();
        case Configuration.UI_MODE_NIGHT_UNDEFINED:
            // We don't know what mode we're in, assume notnight
            Toast.makeText(getApplicationContext(), "Don't know", Toast.LENGTH_SHORT).show();
    }
}

My app shows Toast three times, when I set up MODE_NIGHT_NO in my Activity. Why?

Upd. Sorry. I forgot about break