android--ExpandableListView的简单运用

  ExpandableListView组件是android中一个比较常用的组件，当点击一个父item的时候可以将它的子item显示出来，像手机QQ中的好友列表就是实现的类型效果。使用ExpandableListView组件的关键就是设置它的adapter，这个adapter必须继承BaseExpandbaleListAdapter类，所以实现运用ExpandableListView的核心就是学会继承这个BaseExpanableListAdapter类。

  下面是一个小例子。

activity_main.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.example.expandablelistview.MainActivity">  <ExpandableListView      android:layout_width="match_parent"      android:layout_height="match_parent"      android:id="@+id/list_view"/></RelativeLayout>
goods_item.xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="50dp">    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_marginLeft="7dp"        android:id="@+id/name_tv"/>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_toRightOf="@id/name_tv"        android:layout_marginLeft="7dp"        android:id="@+id/price_tv"/>    <TextView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_gravity="right"        android:layout_alignParentRight="true"        android:id="@+id/selltime_tv"/></RelativeLayout>
selltime.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical" android:layout_width="match_parent"    android:layout_height="match_parent">    <TextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/selltime_tv"        android:textSize="20sp"        android:gravity="left"/></LinearLayout>
Goods.java

package com.example.expandablelistview;/** * Created by Lenovo on 2017/4/24. */public class Goods {    private String name;    private Double price;    private String sellTime;    public Goods(String name, Double price, String sellTime) {        this.name = name;        this.price = price;        this.sellTime = sellTime;    }    public Goods() {    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public Double getPrice() {        return price;    }    public void setPrice(Double price) {        this.price = price;    }    public String getSellTime() {        return sellTime;    }    public void setSellTime(String sellTime) {        this.sellTime = sellTime;    }}

ViewHolder.java

package com.example.expandablelistview;import android.content.Context;import android.util.SparseArray;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;/** * Created by Lenovo on 2017/4/24. */public class ViewHolder {    //保存所有视图的集合    private SparseArray<View> mViews;    //转换视图    private View mConvertView;    private ViewHolder(Context mContext, ViewGroup parent,int layoutId){        mViews = new SparseArray<>();        mConvertView = LayoutInflater.from(mContext).inflate(layoutId,parent,false);        mConvertView.setTag(this);    }    public static ViewHolder get(Context context, View convertView,ViewGroup parent,int layoutId){        ViewHolder viewHolder;        if(convertView == null){            viewHolder = new ViewHolder(context,parent,layoutId);        }else{            viewHolder = (ViewHolder) convertView.getTag();        }        return viewHolder;    }    public <T extends View> T getView(int viewId){        View view = mViews.get(viewId);        //判断视图是否保存过        if(view == null){            view = mConvertView.findViewById(viewId);            mViews.put(viewId,view);        }        return (T)view;    }    /**     * 返回ConvertView     * @return     */    public View getConvertView(){        return mConvertView;    }    public ViewHolder setTextViewText(int viewId,String text){        TextView textView = getView(viewId);        textView.setText(text);        return this;    } }
MyExpandableListViewAdapter.java

package com.example.expandablelistview;import android.content.Context;import android.text.Layout;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseExpandableListAdapter;import java.util.List;import java.util.Map;/** * Created by Lenovo on 2017/4/24. */public class MyExpandableListViewAdapter extends BaseExpandableListAdapter {    //上下文    private Context mContext;    //所有数据    private Map<String,List<Goods>> mData;    //组集合    private List<String> mGroups;    //打气筒    private LayoutInflater mInflater;    //构造函数    public MyExpandableListViewAdapter(Context mContext, Map<String, List<Goods>> mData, List<String> mGroups) {        this.mContext = mContext;        this.mData = mData;        this.mGroups = mGroups;        mInflater = LayoutInflater.from(mContext);    }    //返回组的数量    @Override    public int getGroupCount() {        return mGroups.size();    }    //返回子项目的数量    @Override    public int getChildrenCount(int groupPosition) {        String group = mGroups.get(groupPosition);        List<Goods> list = mData.get(group);        return list.size();    }    //获取组    @Override    public Object getGroup(int groupPosition) {        String group = mGroups.get(groupPosition);        return group;    }    //获取子项目    @Override    public Object getChild(int groupPosition, int childPosition) {        String group = mGroups.get(groupPosition);        List<Goods> list = mData.get(group);        return list.get(childPosition);    }    //获得组的id    @Override    public long getGroupId(int groupPosition) {        return groupPosition;    }    //获取字项目的id    @Override    public long getChildId(int groupPosition, int childPosition) {        return childPosition;    }    //返回组的视图    @Override    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {        ViewHolder viewHolder = ViewHolder.get(mContext,convertView,parent,R.layout.selltime_item);        viewHolder.setTextViewText(R.id.selltime_tv,mGroups.get(groupPosition));        return viewHolder.getConvertView();    }    //返回组中子项目的视图    @Override    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {        ViewHolder viewHolder = ViewHolder.get(mContext,convertView,parent,R.layout.goods_item);        String group = mGroups.get(groupPosition);        List<Goods> list = mData.get(group);        Goods goods = list.get(childPosition);        viewHolder.setTextViewText(R.id.name_tv,goods.getName());        viewHolder.setTextViewText(R.id.price_tv,"价格："+goods.getPrice());        viewHolder.setTextViewText(R.id.selltime_tv,goods.getSellTime());        return viewHolder.getConvertView();    }    @Override    public boolean hasStableIds() {        return false;    }    @Override    public boolean isChildSelectable(int groupPosition, int childPosition) {        return false;    }}
MainActivity.java

package com.example.expandablelistview;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.ExpandableListView;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class MainActivity extends AppCompatActivity {    private ExpandableListView mListView;    private List<Goods> mGoods;    private Map<String,List<Goods>> mData;    private List<String> mGroups;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initData();        initView();    }    private void initView() {        mListView = (ExpandableListView) findViewById(R.id.list_view);        //消掉组上的那个箭头        mListView.setGroupIndicator(null);        MyExpandableListViewAdapter adapter = new MyExpandableListViewAdapter(this,mData,mGroups);        //设置适配器        mListView.setAdapter(adapter);        convertData();        expandGroup();    }    private void initData() {        mGoods = new ArrayList<>();        mData = new HashMap<>();        mGroups = new ArrayList<>();        //模拟数据        mGoods.add(new Goods("苹果电脑",10000.0,"2011-1-1"));        mGoods.add(new Goods("苹果手机",4000.0,"2011-1-1"));        mGoods.add(new Goods("联想电脑",5000.0,"2011-2-2"));        mGoods.add(new Goods("联想手机",3000.0,"2011-2-2"));        mGoods.add(new Goods("华为电脑",5000.0,"2011-3-3"));        mGoods.add(new Goods("华为手机",4000.0,"2011-3-3"));        mGoods.add(new Goods("战神电脑",8000.0,"2011-5-1"));    }    private void expandGroup(){        //一显示界面，就让组全部展开        for(int i = 0; i < mGroups.size(); i++){            mListView.expandGroup(i);        }        //设置监听，返回true代表组不能在合起来        mListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {            @Override            public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {                return true;            }        });    }    /**     * 将数据转变想要的格式     */    private void convertData(){        for(Goods good : mGoods){            //当这个时间不在组中就要添加到组中            if(!mGroups.contains(good.getSellTime())){                mGroups.add(good.getSellTime());                List<Goods> list = new ArrayList<>();                list.add(good);                mData.put(good.getSellTime(),list);            }else{                //已经存在啦，就只用添加子项目                mData.get(good.getSellTime()).add(good);            }        }    }}
运行结果：

   虽然布局比较丑，但是用法就是这样用的，这里的ViewHolder是自己编写成一个通用的ViewHolder了。可以看看。