smooth Scroll AbsListView To Position From Top - Android User Interface

Android examples for User Interface:ListView

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Description

smooth Scroll AbsListView To Position From Top

Demo Code


//package com.java2s;
import android.os.Handler;
import android.support.v4.view.ViewCompat;
import android.view.View;
import android.widget.AbsListView;
import android.widget.AdapterView;

public class Main {
    public static void smoothScrollToPositionFromTop(
            final AbsListView view, final int position) {
        if (view == null || view.getChildCount() == 0) {
            return;
        }/*  w  w w.  j  a va  2s . co m*/

        View child = getChildAtPosition(view, position);
        // There's no need to scroll if child is already at top or view is already scrolled to its end
        if ((child != null)
                && ((child.getTop() == 0 + view.getPaddingTop()) || ((child
                        .getTop() > 0 + view.getPaddingTop()) && !ViewCompat
                        .canScrollVertically(view,
                                ViewCompat.LAYOUT_DIRECTION_RTL)))) {
            return;
        }

        view.setOnScrollListener(new AbsListView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(final AbsListView view,
                    final int scrollState) {
                if (scrollState == SCROLL_STATE_IDLE) {
                    view.setOnScrollListener(null);

                    // Fix for scrolling bug
                    new Handler().post(new Runnable() {
                        @Override
                        public void run() {
                            view.setSelection(position);
                        }
                    });
                }
            }

            @Override
            public void onScroll(final AbsListView view,
                    final int firstVisibleItem, final int visibleItemCount,
                    final int totalItemCount) {
            }
        });

        // Perform scrolling to position
        new Handler().post(new Runnable() {
            @Override
            public void run() {
                view.smoothScrollToPositionFromTop(position, 0, 500);
            }
        });
    }

    public static View getChildAtPosition(AdapterView view, int position) {
        final int numVisibleChildren = view.getChildCount();
        final int firstVisiblePosition = view.getFirstVisiblePosition();

        for (int i = 0; i < numVisibleChildren; i++) {
            int positionOfView = firstVisiblePosition + i;
            if (positionOfView == position) {
                return view.getChildAt(i);
            }
        }
        return null;
    }
}

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