[Android] How to detect if a listview is scrolling up or down

http://blog.evoxmusic.fr/content/android-how-detect-if-listview-scrolling-or-down

Hi there,

just a trick that I find on StackOverflow and adapt (to my case) for ListView instead of ScrollView.

It could be nice to know if you are scrolling up and down over a list to be notified and then do whatever you want.

Here I am gonna explain how to this easily..

There is a method in ListView ListView that reports the shifting of scrolls. It is called onScrollChanged(). However, it is declared protected, so you must create a wrapper class to gain access. For the usage of the method, please check android docs.

First, create an interface to expose the protected method

1. public interface OnScrollListener {
2.     void onScrollUpAndDownChanged(int x, int y, int oldx, int oldy);
3. }

Then, create your wrapper and extend ListView.

1. public class MyCustomListView extends ListView {
2. private OnScrollListener onScrollListener = null;
3.  
4. public MyCustomListView(Context context) {
5.     super(context);
6. }
7.  
8. public MyCustomListView(Context context, AttributeSet attrs, int defStyle) {
9.     super(context, attrs, defStyle);
10. }
11.  
12. public MyCustomListView(Context context, AttributeSet attrs) {
13.     super(context, attrs);
14. }
15.  
16. public void setOnScrollUpAndDownListener(OnScrollListener onScrollListener) {
17.     this.onScrollListener = onScrollListener;
18. }
19.  
20. @Override
21. protected void onScrollChanged(int x, int y, int oldx, int oldy) {
22.     super.onScrollChanged(x, y, oldx, oldy);
23.     if (onScrollListener != null) {
24.         onScrollListener.onScrollUpAndDownChanged(x, y, oldx, oldy);
25.     }
26. }
27. }

Finally, include it in your XML layout like a custom view, and attach listeners like usual.

1. <your mycustomlistview />
2.  
3. myinstance.setOnScrollUpAndDownListener(new OnScrollListener() {...});

Hope this help you to enhance android possibilities like always :)

Cheers

My references: 

- See more at: http://blog.evoxmusic.fr/content/android-how-detect-if-listview-scrolling-or-down#sthash.iYEIREIZ.dpuf