Question

我有gridview，我需要做两件事：

当我向下滚动时，我想找到最后一个可见位置，例如int index = GridView.getLastVisiblePosition();

当我向上滚动时，我想找到第一个可见的位置，例如int index = GridView.getFirstVisiblePosition();

我知道我可以使用以下代码，但我不确定如何以及在何处为ScrollUp和ScrollDown编写代码。请帮我。我是Android的新手。

private OnScrollListener onAnswersScrolled = new OnScrollListener() {

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) {
    }
}

Answer 1

在你的活动中创建全局变量myLastVisiblePos，并为每个FirstVisiblePosition保存，当onScroll事件检查当前FirstVisiblePosition时保存的FirstVisiblePosition如果greate比你上次保存的FirstVisiblePosition那么scrollUp如果小则滚动：

int myLastVisiblePos;// global variable of activity

//save first value when you create GridView
GridView gridView = (GridView) gv.findViewById(R.id.grid_view);
myLastVisiblePos = gridView.getFirstVisiblePosition();

gridView.setOnScrollListener( new OnScrollListener() {
    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
            int currentFirstVisPos = view.getFirstVisiblePosition();
            if(currentFirstVisPos > myLastVisiblePos) {
                //scroll down
            }
            if(currentFirstVisPos < myLastVisiblePos) {
                //scroll up
            }
            myLastVisiblePos = currentFirstVisPos;
    }
});

Answer 2

尝试此代码可能对您有所帮助..

GridView gridView = (GridView) gv.findViewById(R.id.grid_view);
gridView.setOnScrollListener(new OnScrollListener() {

        @Override
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {
            // TODO Auto-generated method stub
            Log.e("GridView","firstVisibleItem"+firstVisibleItem+"\nLastVisibleItem"+totalItemCount);
            }
        }
    });

Android Gridview OnScrollListener ScrollUp和ScrollDown事件

2 个答案: