Question

我有一个网格视图，想要在到达列表结尾后更新网格视图中的项目。为了实现这一点，我决定使用OnScrollListener。但OnScrollListener的行为很奇怪，因为它调用我的方法多次更新网格视图..

@Override
            public void onScroll(AbsListView view, int firstVisibleItem,
                    int visibleItemCount, int totalItemCount) {
                // TODO Auto-generated method stub

                if (firstVisibleItem + visibleItemCount >= totalItemCount) {
                    // End has been reached
                    // Call method to update

                Log.i("CountShit", String.valueOf(firstVisibleItem) + " + "
                        + String.valueOf(visibleItemCount) + " >= "
                        + String.valueOf(totalItemCount));
                }
            }
        });

并且在我的日志中多次调用if conditioin，因为onScrollListener一直在监听滚动我猜...

09-29 14:06:10.338: I/CountShit(23640): 12 + 8 >= 20
09-29 14:06:10.353: I/CountShit(23640): 12 + 8 >= 20
09-29 14:06:10.369: I/CountShit(23640): 12 + 8 >= 20
09-29 14:06:10.385: I/CountShit(23640): 12 + 8 >= 20
09-29 14:06:10.400: I/CountShit(23640): 12 + 8 >= 20
09-29 14:06:10.424: I/CountShit(23640): 14 + 6 >= 20
09-29 14:06:10.439: I/CountShit(23640): 14 + 6 >= 20
09-29 14:06:10.455: I/CountShit(23640): 14 + 6 >= 20
09-29 14:06:10.470: I/CountShit(23640): 14 + 6 >= 20
09-29 14:06:10.486: I/CountShit(23640): 14 + 6 >= 20

有没有一种方法，如果我第一次点击列表的末尾，我的upate方法被调用..然后如果用户向上或向下滚动或者不应该再次调用任何方法！（直到我到达我更新的课程列表的末尾）。

Answer 1

你正在寻求一个无尽的观点。您必须创建一个无限滚动侦听器并将其应用于GridView。请尝试下面的代码;

初始化GridView并应用适配器

final GridView g = (GridView) findViewById(R.id.myGrid);
        g.setAdapter(new ImageAdapter(this));
        EndlessScrollListener scrollListener=new EndlessScrollListener(g,new RefreshList() {

            @Override
            public void onRefresh(int pageNumber) {
                System.out.println("On Refresh invoked..");

            }
        });
        g.setOnScrollListener(scrollListener);

<强> EndlessScrollListener

public class EndlessScrollListener implements OnScrollListener {

    private GridView gridView;
    private boolean isLoading;
    private boolean hasMorePages;
    private int pageNumber=0;
    private RefreshList refreshList;
    private boolean isRefreshing;

    public EndlessScrollListener(GridView gridView,RefreshList refreshList) {
        this.gridView = gridView;
        this.isLoading = false;
        this.hasMorePages = true;
        this.refreshList=refreshList;
    }

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
        if (gridView.getLastVisiblePosition() + 1 == totalItemCount && !isLoading) {
            isLoading = true;
            if (hasMorePages&&!isRefreshing) {
                isRefreshing=true;
                refreshList.onRefresh(pageNumber);
            }
        } else {
            isLoading = false;
        }

    }

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

    }

    public void noMorePages() {
        this.hasMorePages = false;
    }

    public void notifyMorePages(){
        isRefreshing=false;
        pageNumber=pageNumber+1;
    }

    public interface RefreshList {
        public void onRefresh(int pageNumber);
    }
}

Source

Answer 2

totalDataCount - ＆gt;变量，用于存储api为您提供的数据总数

previousTotal - ＆gt;存储先前总计数的变量。默认设置为零。

加载 - ＆gt;布尔值默认设置为false。

在您的活动中声明所有这些变量，而不是在内部类（下面）中声明

此代码可在以下位置使用： -

public class EndlessScrollListenerUser implements OnScrollListener {
    boolean loading = true;

    public EndlessScrollListenerUser() {}

    @Override
    public void onScroll(AbsListView view, int firstVisibleItem,
            int visibleItemCount, int totalItemCount) {
        int lastInScreen = firstVisibleItem + visibleItemCount;
        if (loading) {
            if (totalItemCount > previousTotal) {
                loading = false;
                previousTotal = totalItemCount;
            }
        }
        if (!loading && lastInScreen==totalItemCount && totalDataCount>takeUser && (previousTotal)<totalDataCount) {

            // Your API Call Goes Here after reaching end
            loading = true;
        }
    }

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

Answer 3

我能够通过添加一些变量来解决问题

        private int previousTotal = 0;
        private boolean loading = true;
        private int visibleThreshold = 5;

并检查以下情况..

        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {
            // TODO Auto-generated method stub
            if (loading) {
                if (totalItemCount > previousTotal) {
                    loading = false;
                    previousTotal = totalItemCount;
                    pageCount++;
                }
            }
            if (!loading
                    && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)) {
                // End has been reached
                Log.i("CountShit", String.valueOf(firstVisibleItem) + " + "
                        + String.valueOf(visibleItemCount) + " >= "
                        + String.valueOf(totalItemCount));
                // call update method here
                loading = true;
            }
        }
    });

OnScrollListener更新GridView

3 个答案: