问在ListView中检测向上滚动和向下滚动
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Stack Overflow用户

提问于 2013-05-28 19:37:39

回答 16查看 124.9K关注 0票数 71

我有以下要求：

首先，从服务器获取第2页的数据，并将这些项目填充到ListView中。

考虑到前一页和下一页在场景中都可用，添加了以下代码：

 if(prevPageNo > 0){
    mListViewActual.setOnScrollListener(this);
 }

 if(nextPageNo > 0){
    mListViewActual.setOnScrollListener(this);
 }

我应该设置什么条件来检测向上滚动和向下滚动以下方法：

onScroll(AbsListView视图，int firstVisibleItem，int visibleItemCount，int totalItemCount)
void onScrollStateChanged(AbsListView视图，int scrollState)

在检测到操作:向上滚动和向下滚动之后，相应地将使用前一页编号或下一页编号调用服务，以获取要在Listview中填充的项。

任何输入都会很有帮助。

浏览了以下链接，但未返回正确的向上/向下滚动操作：

link 1 link 2

android

android-listview

scrollbar

回答 16

Stack Overflow用户

发布于 2013-06-10 13:43:10

尝试使用setOnScrollListener并使用scrollState实现onScrollStateChanged

setOnScrollListener(new OnScrollListener(){
    public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
      // TODO Auto-generated method stub
    }
    public void onScrollStateChanged(AbsListView view, int scrollState) {
      // TODO Auto-generated method stub
      final ListView lw = getListView();

       if(scrollState == 0) 
      Log.i("a", "scrolling stopped...");


        if (view.getId() == lw.getId()) {
        final int currentFirstVisibleItem = lw.getFirstVisiblePosition();
         if (currentFirstVisibleItem > mLastFirstVisibleItem) {
            mIsScrollingUp = false;
            Log.i("a", "scrolling down...");
        } else if (currentFirstVisibleItem < mLastFirstVisibleItem) {
            mIsScrollingUp = true;
            Log.i("a", "scrolling up...");
        }

        mLastFirstVisibleItem = currentFirstVisibleItem;
    } 
    }
  });

票数 94

Stack Overflow用户

发布于 2013-12-12 18:24:26

以下是上述一些解决方案的工作修改版本。

添加另一个类ListView：

package com.example.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;

public class ListView extends android.widget.ListView {

    private OnScrollListener onScrollListener;
    private OnDetectScrollListener onDetectScrollListener;

    public ListView(Context context) {
        super(context);
        onCreate(context, null, null);
    }

    public ListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        onCreate(context, attrs, null);
    }

    public ListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        onCreate(context, attrs, defStyle);
    }

    @SuppressWarnings("UnusedParameters")
    private void onCreate(Context context, AttributeSet attrs, Integer defStyle) {
        setListeners();
    }

    private void setListeners() {
        super.setOnScrollListener(new OnScrollListener() {

            private int oldTop;
            private int oldFirstVisibleItem;

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (onScrollListener != null) {
                    onScrollListener.onScrollStateChanged(view, scrollState);
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (onScrollListener != null) {
                    onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
                }

                if (onDetectScrollListener != null) {
                    onDetectedListScroll(view, firstVisibleItem);
                }
            }

            private void onDetectedListScroll(AbsListView absListView, int firstVisibleItem) {
                View view = absListView.getChildAt(0);
                int top = (view == null) ? 0 : view.getTop();

                if (firstVisibleItem == oldFirstVisibleItem) {
                    if (top > oldTop) {
                        onDetectScrollListener.onUpScrolling();
                    } else if (top < oldTop) {
                        onDetectScrollListener.onDownScrolling();
                    }
                } else {
                    if (firstVisibleItem < oldFirstVisibleItem) {
                        onDetectScrollListener.onUpScrolling();
                    } else {
                        onDetectScrollListener.onDownScrolling();
                    }
                }

                oldTop = top;
                oldFirstVisibleItem = firstVisibleItem;
            }
        });
    }

    @Override
    public void setOnScrollListener(OnScrollListener onScrollListener) {
        this.onScrollListener = onScrollListener;
    }

    public void setOnDetectScrollListener(OnDetectScrollListener onDetectScrollListener) {
        this.onDetectScrollListener = onDetectScrollListener;
    }
}

和一个接口：

public interface OnDetectScrollListener {

    void onUpScrolling();

    void onDownScrolling();
}

最后是如何使用：

com.example.view.ListView listView = (com.example.view.ListView) findViewById(R.id.list);
listView.setOnDetectScrollListener(new OnDetectScrollListener() {
    @Override
    public void onUpScrolling() {
        /* do something */
    }

    @Override
    public void onDownScrolling() {
        /* do something */
    }
});

在XML布局中：

<com.example.view.ListView
    android:id="@+id/list"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>

这是我的第一个话题，请不要苛刻地评价我。=)

票数 63

Stack Overflow用户

发布于 2014-06-03 16:34:22

这是一个简单的实现：

lv.setOnScrollListener(new OnScrollListener() {
        private int mLastFirstVisibleItem;

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

        }

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

            if(mLastFirstVisibleItem<firstVisibleItem)
            {
                Log.i("SCROLLING DOWN","TRUE");
            }
            if(mLastFirstVisibleItem>firstVisibleItem)
            {
                Log.i("SCROLLING UP","TRUE");
            }
            mLastFirstVisibleItem=firstVisibleItem;

        }
    });

如果你需要更高的精度，你可以使用这个自定义的ListView类：

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.AbsListView;
import android.widget.ListView;

/**
 * Created by root on 26/05/15.
 */
public class ScrollInterfacedListView extends ListView {


    private OnScrollListener onScrollListener;
    private OnDetectScrollListener onDetectScrollListener;

    public ScrollInterfacedListView(Context context) {
        super(context);
        onCreate(context, null, null);
    }

    public ScrollInterfacedListView(Context context, AttributeSet attrs) {
        super(context, attrs);
        onCreate(context, attrs, null);
    }

    public ScrollInterfacedListView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        onCreate(context, attrs, defStyle);
    }

    @SuppressWarnings("UnusedParameters")
    private void onCreate(Context context, AttributeSet attrs, Integer defStyle) {
        setListeners();
    }

    private void setListeners() {
        super.setOnScrollListener(new OnScrollListener() {

            private int oldTop;
            private int oldFirstVisibleItem;

            @Override
            public void onScrollStateChanged(AbsListView view, int scrollState) {
                if (onScrollListener != null) {
                    onScrollListener.onScrollStateChanged(view, scrollState);
                }
            }

            @Override
            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
                if (onScrollListener != null) {
                    onScrollListener.onScroll(view, firstVisibleItem, visibleItemCount, totalItemCount);
                }

                if (onDetectScrollListener != null) {
                    onDetectedListScroll(view, firstVisibleItem);
                }
            }

            private void onDetectedListScroll(AbsListView absListView, int firstVisibleItem) {
                View view = absListView.getChildAt(0);
                int top = (view == null) ? 0 : view.getTop();

                if (firstVisibleItem == oldFirstVisibleItem) {
                    if (top > oldTop) {
                        onDetectScrollListener.onUpScrolling();
                    } else if (top < oldTop) {
                        onDetectScrollListener.onDownScrolling();
                    }
                } else {
                    if (firstVisibleItem < oldFirstVisibleItem) {
                        onDetectScrollListener.onUpScrolling();
                    } else {
                        onDetectScrollListener.onDownScrolling();
                    }
                }

                oldTop = top;
                oldFirstVisibleItem = firstVisibleItem;
            }
        });
    }

    @Override
    public void setOnScrollListener(OnScrollListener onScrollListener) {
        this.onScrollListener = onScrollListener;
    }

    public void setOnDetectScrollListener(OnDetectScrollListener onDetectScrollListener) {
        this.onDetectScrollListener = onDetectScrollListener;
    }


    public interface OnDetectScrollListener {

        void onUpScrolling();

        void onDownScrolling();
    }

}

一个使用示例：(不要忘记将其作为Xml标签添加到layout.xml中)

scrollInterfacedListView.setOnDetectScrollListener(new ScrollInterfacedListView.OnDetectScrollListener() {
            @Override
            public void onUpScrolling() {
               //Do your thing
            }

            @Override
            public void onDownScrolling() {

             //Do your thing
            }
        });

票数 47

页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://stackoverflow.com/questions/16791100

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