Android: Detect softkeyboard open

Here is my solution:

1/ A simple interface

public interface KeyboardVisibilityListener {
    void onKeyboardVisibilityChanged(boolean keyboardVisible);
}

2/ A utility method (put it where you want, for instance in a class named KeyboardUtil)

public static void setKeyboardVisibilityListener(Activity activity, KeyboardVisibilityListener keyboardVisibilityListener) {
    View contentView = activity.findViewById(android.R.id.content);
    contentView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
        private int mPreviousHeight;

        @Override
        public void onGlobalLayout() {
            int newHeight = contentView.getHeight();
            if (mPreviousHeight != 0) {
                if (mPreviousHeight > newHeight) {
                    // Height decreased: keyboard was shown
                    keyboardVisibilityListener.onKeyboardVisibilityChanged(true);
                } else if (mPreviousHeight < newHeight) {
                    // Height increased: keyboard was hidden
                    keyboardVisibilityListener.onKeyboardVisibilityChanged(false);
                } else {
                    // No change
                }
            }
            mPreviousHeight = newHeight;
        }
    });
}

3/ Use from an Activity this way (a good place is in onCreate):

KeyboardUtil.setKeyboardVisibilityListener(this, mKeyboardVisibilityListener);