How to syncronisize two Listview positions

Question

I have two ListViews. Is there any way to synchronize the position of ListViews when I scroll any one of the Lists. Im implementing an AbsListView.OnScrollListener, registering to the ListView. When the ListView is scrolled, the onScroll() method of OnScrollListener will be triggered, then i call `smoothScrollToPosition()'. But it doent work properly. Can someone provide me any code example for this?

Because im trying to create my own Compound Control that has to be implemented with 2 listView and with other components as well. — arkmetal, Aug 10 '12 at 18:09
I guess I just don't understand the purpose, If the lists always scroll together, it belongs together and can go in a single list with multiple lines or columns (IMO). Or is this something where you set the positions relative.to each other THEN lock the scrolling? — Barak, Aug 10 '12 at 18:49
Ok maybe i explain it in the wrong way, the other listview can be scrollable vertically and horizontally, but when i want to scroll it vertically, it has to move with other listview as well, then when you scroll it horizantally you can scroll only that list view horinzally and the other stays fixed. — arkmetal, Aug 10 '12 at 19:00
Listview only scrolls vertically, to scroll on the horizontal you can use a ScrollView. — Marcio Covre, Aug 10 '12 at 19:33
what??? in order to scroll horizontally you use HorizontalScrollView. — arkmetal, Aug 10 '12 at 19:39
Another sollution is [here][1], It works for me [1]: https://stackoverflow.com/questions/12342419/android-scrolling-2-listviews-together — shyam.y, Jun 17 '14 at 12:28

score 5 · Answer 1 · answered Apr 23 '13 at 11:56

Here is a working code sample of what nininho is suggesting

MainActivity

public class MainActivity extends Activity {

public static String[] Cheeses = new String[] { "Abbaye de Belloc", "Abbaye du Mont des Cats",
        "Abertam", "Abondance", "Ackawi", "Acorn", "Adelost", "Affidelice au Chablis",
        "Afuega'l Pitu", "Airag", "Airedale", "Aisy Cendre", "Allgauer Emmentaler", "Alverca",
        "Ambert", "American Cheese", };

ListView list1;
ListView list2;

boolean isLeftListEnabled = true;
boolean isRightListEnabled = true;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ListAdapter adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,
            Cheeses);

    list1 = (ListView) findViewById(R.id.list1);
    list1.setAdapter(adapter);

    list2 = (ListView) findViewById(R.id.list2);
    list2.setAdapter(adapter);

    // IF YOU DO NOT OVERRIDE THIS
    // ONLY THE ONE THAT IS TOUCHED WILL SCROLL OVER
    list1.setOverScrollMode(ListView.OVER_SCROLL_NEVER);
    list2.setOverScrollMode(ListView.OVER_SCROLL_NEVER);

    list1.setOnScrollListener(new OnScrollListener() {

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            // onScroll will be called and there will be an infinite loop.
            // That's why i set a boolean value
            if (scrollState == SCROLL_STATE_TOUCH_SCROLL) {
                isRightListEnabled = false;
            } else if (scrollState == SCROLL_STATE_IDLE) {
                isRightListEnabled = true;
            }
        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
                int totalItemCount) {
            View c = view.getChildAt(0);
            if (c != null && isLeftListEnabled) {
                list2.setSelectionFromTop(firstVisibleItem, c.getTop());
            }
        }
    });

    list2.setOnScrollListener(new OnScrollListener() {
        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            if (scrollState == SCROLL_STATE_TOUCH_SCROLL) {
                isLeftListEnabled = false;
            } else if (scrollState == SCROLL_STATE_IDLE) {
                isLeftListEnabled = true;
            }
        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
                int totalItemCount) {
            View c = view.getChildAt(0);
            if (c != null && isRightListEnabled) {
                list1.setSelectionFromTop(firstVisibleItem, c.getTop());
            }
        }
    });
}
}

the XML

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:splitMotionEvents="true">
    <ListView android:id="@+id/list1"
              android:layout_width="0dip"
              android:layout_height="match_parent"
              android:layout_weight="1" />
    <ListView android:id="@+id/list2"
              android:layout_width="0dip"
              android:layout_height="match_parent"
              android:layout_weight="1" />
</LinearLayout>

this won't work if items are not all the same size, will it ? — mbonnin, Feb 09 '15 at 10:20
No... well it does work but you probably won't have the effect that you would like to have. But it's a bit out dated. If i were you i would check out the RecyclerView. Here's a good explanation of how it works http://wiresareobsolete.com/2014/09/building-a-recyclerview-layoutmanager-part-1/ — EvertvdBraak, Feb 10 '15 at 08:53

score 1 · Answer 2 · answered Aug 10 '12 at 17:57

1

If the position is visible smoothScrollToPosition() won't scroll. You can thought use scrollTo or scrollBy on the other list that is not scrolling at the moment, but be careful to not enter a recursion with each list calling the other to scroll.

answered Aug 10 '12 at 17:57

Marcio Covre

4,556
2
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But in that case, if i use scrollTo or scrollBy, is gonna move only the rendered items but it doesnt work as an adapter. – arkmetal Aug 13 '12 at 20:45
No, it's not on the adapter, the scroll is on the view, so you can have a scroll that shows only part of the item. You may also try public void smoothScrollToPositionFromTop (int position, int offset) to force scroll the item to top, but to be the two lists in sync you need to call this on both lists. – Marcio Covre Aug 14 '12 at 12:13

How to syncronisize two Listview positions

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