ExtendableListViewAdapter的简单用法

预览图：
就如同QQ联系人界面

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image.png

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总的需要准备三个布局文件:
主界面的布局、父布局、子布局

image.png

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主布局文件：

父布局文件：就放了一个文本控件

子布局文件：左边放一张图片，右边是文字

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定义一个子布局的类

package com.example.expandablelistviewtest;

public class Item {
    private int imgId;
    private String des;
    Item (int imgId,String des){
        this.imgId=imgId;
        this.des=des;
    }
    public int getImgId() {
        return imgId;
    }
    public void setImgId(int imgId) {
        this.imgId = imgId;
    }
    public String getDes() {
        return des;
    }
    public void setDes(String des) {
        this.des = des;
    }
}

和ListView一样也需要适配器

package com.example.expandablelistviewtest;

import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

public class MyExtendableListViewAdapter extends BaseExpandableListAdapter {
    private static final String TAG = "pos";
    //子列表
    private ArrayList>iChildList;
    //父列表
    private ListparentList;

    MyExtendableListViewAdapter(ListparentList,List> iChildList){
        this.parentList=parentList;
        this.iChildList= (ArrayList>) iChildList;
    }
    @Override
    // 获取分组的个数
    public int getGroupCount() {
        return parentList.size();
    }

    //获取指定分组中的子选项的个数
    @Override
    public int getChildrenCount(int groupPosition) {
        Log.d(TAG, "getChildrenCount: "+groupPosition);
        return iChildList.size();
    }

    //        获取指定的分组数据
    @Override
    public Object getGroup(int groupPosition) {
        Log.d(TAG, "getGroup: "+groupPosition);
        return parentList.get(groupPosition);
    }

    //获取指定分组中的指定子选项数据
    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return iChildList.get(groupPosition).get(childPosition);
    }

    //获取指定分组的ID, 这个ID必须是唯一的
    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    //获取子选项的ID, 这个ID必须是唯一的
    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    //分组和子选项是否持有稳定的ID, 就是说底层数据的改变会不会影响到它们
    @Override
    public boolean hasStableIds() {
        return false;
    }
    /**
     *
     * 获取显示指定组的视图对象
     *
     * @param groupPosition 组位置
     * @param isExpanded 该组是展开状态还是伸缩状态
     * @param convertView 重用已有的视图对象
     * @param parent 返回的视图对象始终依附于的视图组
     */
// 获取显示指定分组的视图
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        GroupViewHolder groupViewHolder;
        if (convertView == null){
            convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.partent_item,parent,false);
            groupViewHolder = new GroupViewHolder(convertView);
            convertView.setTag(groupViewHolder);
        }else {
            groupViewHolder = (GroupViewHolder)convertView.getTag();
        }
        groupViewHolder.tvTitle.setText(parentList.get(groupPosition));
        return convertView;
    }
    /**
     *
     * 获取一个视图对象，显示指定组中的指定子元素数据。
     *
     * @param groupPosition 组位置
     * @param childPosition 子元素位置
     * @param isLastChild 子元素是否处于组中的最后一个
     * @param convertView 重用已有的视图(View)对象
     * @param parent 返回的视图(View)对象始终依附于的视图组
     * @return
     * @see android.widget.ExpandableListAdapter#getChildView(int, int, boolean, android.view.View,
     *      android.view.ViewGroup)
     */

    //取得显示给定分组给定子位置的数据用的视图
    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        ChildViewHolder childViewHolder;
        if (convertView==null){
            convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item,parent,false);
            childViewHolder = new ChildViewHolder(convertView);
            convertView.setTag(childViewHolder);

        }else {
            childViewHolder = (ChildViewHolder) convertView.getTag();
        }
        childViewHolder.tvTitle.setText(iChildList.get(groupPosition).get(childPosition).getDes());
        childViewHolder.imageView.setImageResource(iChildList.get(groupPosition).get(childPosition).getImgId());
        return convertView;
    }

    //指定位置上的子元素是否可选中
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    static class GroupViewHolder {
        TextView tvTitle;
        GroupViewHolder(View convertView){
            tvTitle = convertView.findViewById(R.id.label_group_normal);
        }
    }

    static class ChildViewHolder {
        TextView tvTitle;
        ImageView imageView;
        ChildViewHolder(View convertView){
            tvTitle = convertView.findViewById(R.id.tv_name);
            imageView=convertView.findViewById(R.id.img_icon);
        }
    }
}

• 继承BaseExpandableListAdapter，需要重写十个方法

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主活动代码

package com.example.expandablelistviewtest;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    //装子项的泛型数据
    private ArrayList>iChildList=new ArrayList<>();
    private ExpandableListView expandableListView;
    private ListparentList=new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //准备数据
        initData();

        expandableListView=findViewById(R.id.expend_list);
        expandableListView.setAdapter(new MyExtendableListViewAdapter(parentList,iChildList));
        //设置分组的监听
        expandableListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
            @Override
            public boolean onGroupClick(ExpandableListView expandableListView, View view, int groupPosition, long l) {
                Toast.makeText(getApplicationContext(), parentList.get(groupPosition), Toast.LENGTH_SHORT).show();
                return false;
            }
        });
        //设置子项布局监听
        expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                Toast.makeText(getApplicationContext(), iChildList.get(groupPosition).get(childPosition).getDes(), Toast.LENGTH_SHORT).show();
                return true;
            }
        });
        //控制他只能打开一个组
        expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
            @Override
            public void onGroupExpand(int groupPosition) {
                int count = parentList.size();
                for(int i = 0;i < count;i++){
                    if (i!=groupPosition){
                        expandableListView.collapseGroup(i);
                    }
                }
            }
        });
    }
    //用链表
    public void initData(){
       parentList.add("索隆 ");
       parentList.add("乔巴");
       parentList.add("山治");
       parentList.add("路飞");

        ArrayList iData = new ArrayList<>();
        Item item1=new Item(R.drawable.aaa,"第一");
        iData.add(item1);
        Item item2=new Item(R.drawable.bbb,"第二");
        iData.add(item2);
        Item item3=new Item(R.drawable.ccc,"第三");
        iData.add(item3);
        Item item4=new Item(R.drawable.ddd,"第四");
        iData.add(item4);
        iChildList.add(iData);

        ArrayList iData2 = new ArrayList<>();
        Item item5=new Item(R.drawable.aaa,"第一");
        iData2.add(item5);
        Item item6=new Item(R.drawable.bbb,"第二");
        iData2.add(item6);
        Item item7=new Item(R.drawable.ccc,"第三");
        iData2.add(item7);
        Item item8=new Item(R.drawable.ddd,"第四");
        iData2.add(item8);
        iChildList.add(iData2);

        ArrayList iData3 = new ArrayList<>();
        Item item9=new Item(R.drawable.aaa,"第一");
        iData3.add(item9);
        Item item10=new Item(R.drawable.bbb,"第二");
        iData3.add(item10);
        Item item11=new Item(R.drawable.ccc,"第三");
        iData3.add(item11);
        Item item12=new Item(R.drawable.ddd,"第四");
        iData3.add(item12);
        iChildList.add(iData3);

        ArrayList iData4 = new ArrayList<>();
        Item item13=new Item(R.drawable.aaa,"第一");
        iData4.add(item13);
        Item item14=new Item(R.drawable.bbb,"第二");
        iData4.add(item14);
        Item item15=new Item(R.drawable.ccc,"第三");
        iData4.add(item15);
        Item item16=new Item(R.drawable.ddd,"第四");
        iData4.add(item16);
        iChildList.add(iData4);
    }
}