Custom ScrollView code instance in Android

ScrollView in Android is very simple, there is no OnScrollListener like ListView1, but it doesn't matter, we can inherit from ScrollView to customize 1 OnScrollListener. Without further ado, just code:

public class ObservableScrollView extends ScrollView {
    public ObservableScrollView(Context context) {

        super(context);

    }
    public ObservableScrollView(Context context, AttributeSet attrs) {

        super(context, attrs);

    }
    public ObservableScrollView(Context context, AttributeSet attrs, int defStyle) {

        super(context, attrs, defStyle);

    }
    public interface OnScrollChangedListener {

        public void onScrollChanged(int x, int y, int oldX, int oldY);

    }
    private OnScrollChangedListener onScrollChangedListener;
    public void setOnScrollListener(OnScrollChangedListener onScrollChangedListener) {

        this.onScrollChangedListener = onScrollChangedListener;

    }
    @Override

    protected void onScrollChanged(int x, int y, int oldX, int oldY) {

        super.onScrollChanged(x, y, oldX, oldY);

        if (onScrollChangedListener != null) {

            onScrollChangedListener.onScrollChanged(x, y, oldX, oldY);

        }

    }

}

The above code is very simple, and I believe you can understand it. When you use it, you only need to call setOnScrollListener method. There are four parameters in it > oldY slides down and vice versa. There are other interesting things you can do, like determine if ScrollView is sliding to a particular location and do some animation, and more creatively it's up to you to think for yourself.