ListView滚动监听

来源：互联网发布：云计算和传统的区别编辑：程序博客网时间：2024/05/21 12:47

先展示效果:
这里写图片描述

布局:

<?xml version="1.0" encoding="utf-8"?><LinearLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_main"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    tools:context="com.eg.lyx.listviewdemo.MainActivity">    <TextView        android:id="@+id/tv"        android:layout_width="match_parent"        android:layout_height="40dp"        android:gravity="center"        android:text="标题"        android:textColor="#e21b1b"        />    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:scrollbars="none"/></LinearLayout>

代码:

package com.eg.lyx.listviewdemo;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.util.SparseArray;import android.view.MotionEvent;import android.view.View;import android.widget.AbsListView;import android.widget.ListView;import android.widget.TextView;import java.util.ArrayList;import java.util.List;import static android.R.attr.data;import static android.R.attr.y;public class MainActivity extends AppCompatActivity {    private TextView tv;    private ListView lv;    private List<String> data = new ArrayList<>();    private int lastVisibleItemPosition = 0;    private int mLastFirstPostion = 0;    private int mLastFirstTop;    private int touchSlop;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        tv = (TextView) findViewById(R.id.tv);        lv = (ListView) findViewById(R.id.lv);        initData();        lv.setAdapter(new MyAdapter(MainActivity.this, data));        // 还有一种方法，直接给ListView设置onTouchListener，在MOVE事件去判断这一次的y坐        // 标和上一次的y坐标大小关系从而进行判断，但是这样有个缺陷就是，当我们手指快速滑        // 动然后抬起的情况下，这时候ListView并没有马上停止仍会自动滑一段距离，而此时回调        // 却因为MOVE事件的不再产生无法继续执行回调。        lv.setOnScrollListener(new AbsListView.OnScrollListener() {            @Override            public void onScrollStateChanged(AbsListView view, int scrollState) {                switch (scrollState) {                    case SCROLL_STATE_IDLE://停止滑动时                        break;                    case SCROLL_STATE_TOUCH_SCROLL://正在滚动                        break;                    case SCROLL_STATE_FLING:                        break;                }            }            @Override            public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {                int currentTop;                View firstChildView = view.getChildAt(0);                if (firstChildView != null) {                    currentTop = view.getChildAt(0).getTop();                } else {                    //ListView初始化的时候会回调onScroll方法，此时getChildAt(0)仍是为空的                    return;                }                //判断上次可见的第一个位置和这次可见的第一个位置                if (firstVisibleItem != mLastFirstPostion) {                    //不是同一个位置                    if (firstVisibleItem > mLastFirstPostion) {                        //TODO do down//                        Log.i("cs", "--->down");                        int firstVisiblePosition = view.getFirstVisiblePosition();                        Log.i("cs", "firstVisiblePosition--->" + firstVisiblePosition);                        tv.setText(data.get(firstVisiblePosition) + "    DOWN");                    } else {                        //TODO do up//                        Log.i("cs", "--->up");                        int firstVisiblePosition = view.getFirstVisiblePosition();                        Log.i("cs", "firstVisiblePosition--->" + firstVisiblePosition);                        tv.setText(data.get(firstVisiblePosition) + "    UP");                    }                    mLastFirstTop = currentTop;                } else {                    //是同一个位置                    int firstVisiblePosition = view.getFirstVisiblePosition();                    Log.i("cs", "firstVisiblePosition--->" + firstVisiblePosition);                    if (Math.abs(currentTop - mLastFirstTop) > touchSlop) {                        //避免动作执行太频繁或误触，加入touchSlop判断，具体值可进行调整                        if (currentTop > mLastFirstTop) {                            //TODO :do up//                            Log.i("cs", "equals--->up");                        } else if (currentTop < mLastFirstTop) {                            //TODO :do down//                            Log.i("cs", "equals--->down");                        }                        mLastFirstTop = currentTop;                    }                }                mLastFirstPostion = firstVisibleItem;            }        });    }    private void initData() {        for (int i = 0; i < 20; i++) {            data.add("卡片" + i);        }    }}

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