How do I detect if software keyboard is visible on Android Device or not?

This works for me. Maybe this is always the best way for all versions.

It would be effective to make a property of keyboard visibility and observe this changes delayed because the onGlobalLayout method calls many times. Also it is good to check the device rotation and windowSoftInputMode is not adjustNothing.

boolean isKeyboardShowing = false;
void onKeyboardVisibilityChanged(boolean opened) {
    print("keyboard " + opened);
}

// ContentView is the root view of the layout of this activity/fragment    
contentView.getViewTreeObserver().addOnGlobalLayoutListener(
    new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {

        Rect r = new Rect();
        contentView.getWindowVisibleDisplayFrame(r);
        int screenHeight = contentView.getRootView().getHeight();

        // r.bottom is the position above soft keypad or device button.
        // if keypad is shown, the r.bottom is smaller than that before.
        int keypadHeight = screenHeight - r.bottom;

        Log.d(TAG, "keypadHeight = " + keypadHeight);

        if (keypadHeight > screenHeight * 0.15) { // 0.15 ratio is perhaps enough to determine keypad height.
            // keyboard is opened
            if (!isKeyboardShowing) {
                isKeyboardShowing = true
                onKeyboardVisibilityChanged(true)
            }
        }
        else {
            // keyboard is closed
            if (isKeyboardShowing) {
                isKeyboardShowing = false
                onKeyboardVisibilityChanged(false)
            }
        }
    }
});