ExpandableListView

Adapter：

package com.example.websocketchaifen.activity;

import android.content.Context;
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 com.example.websocketchaifen.R;

import java.util.List;

/**
 * author : ZJS
 * e-mail : 15574564770@163.com
 * date   : 20-9-4上午11:25
 * desc   :
 * version : 1.0
 */
public class myAdapter extends BaseExpandableListAdapter {

    Context context;
    LayoutInflater mInflater;
    String[] mGroupStrings;
    List<List<Item>> mData;

    public myAdapter(Context context, List<List<Item>> mData) {
        this.context = context;
        this.mData = mData;
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        mGroupStrings = new String[]{"第1个", "第2个", "第3个", "第4个"};

    }

    //获取子列表项对应的Item
    @Override
    public Item getChild(int groupPosition, int childPosition) {
        return mData.get(groupPosition).get(childPosition);
    }

    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    //获得子列表项的数目
    @Override
    public int getChildrenCount(int groupPosition) {
        return mData.get(groupPosition).size();
    }

    //获得父列表项
    @Override
    public Object getGroup(int groupPosition) {
        return mData.get(groupPosition);
    }

    //获得父列表项的数目
    @Override
    public int getGroupCount() {
        return mData.size();
    }

    //获得父列表项的Id
    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    @Override
    public boolean hasStableIds() {
        return false;
    }

    //子列表项是否能否触发事件，返回true则为可以响应点击
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.group_item_layout, null);
        }
        GroupViewHolder holder = new GroupViewHolder();
        holder.mGroupName = (TextView) convertView.findViewById(R.id.group_name);
        holder.mGroupName.setText(mGroupStrings[groupPosition]);
        holder.mGroupCount = (TextView) convertView.findViewById(R.id.group_number);
        holder.mGroupCount.setText("[" + mData.get(groupPosition).size() + "]");

        return convertView;
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        if (convertView == null) {
            //如果第一次调用则convertView为null，需要获得对应的layout布局文件：子列表项的布局R.layout.child_item_layout
            convertView = mInflater.inflate(R.layout.child_item_layout, null);
        }
        //子列表项的布局文件的View类，具体看下面的类定义
        ChildViewHolder holder = new ChildViewHolder();
        holder.mIcon = (ImageView) convertView.findViewById(R.id.img);
        holder.mChildName = (TextView) convertView.findViewById(R.id.item_name);
        holder.mChildName.setText(getChild(groupPosition, childPosition).getName());
        holder.mDetail = (TextView) convertView.findViewById(R.id.item_detail);
        holder.mDetail.setText(getChild(groupPosition, childPosition).getDetail());
        return convertView;
    }

    private class GroupViewHolder {
        TextView mGroupName;
        TextView mGroupCount;
    }
    private class ChildViewHolder {
        ImageView mIcon;
        TextView mChildName;
        TextView mDetail;
    }
}

bean

package com.example.websocketchaifen.activity;

/**
 * author : ZJS
 * e-mail : 15574564770@163.com
 * date   : 20-9-4上午11:26
 * desc   :
 * version : 1.0
 */
public class Item {
    private int resId;            //图片（头像）的Id
    private String name;    //子列表项的名字（QQ昵称）
    private String detail;    //子列表项的详细信息（QQ签名）

    public int getResId() {
        return resId;
    }

    public void setResId(int resId) {
        this.resId = resId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDetail() {
        return detail;
    }

    public void setDetail(String detail) {
        this.detail = detail;
    }
}

main_layout

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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=".activity.ceshi">

    <ExpandableListView
        android:id="@+id/expandableListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1" />
</androidx.constraintlayout.widget.ConstraintLayout>

child_item_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/icon_lx_n" />

    <TextView
        android:text="aaaa"
        android:id="@+id/item_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:text="aaaaaaaa"
        android:id="@+id/item_detail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

group_layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:gravity="center_horizontal"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/group_name"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="AAAA" />

        <TextView
            android:id="@+id/group_number"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:text="AAAA" />
    </LinearLayout>

</LinearLayout>

main_activity

package com.example.websocketchaifen.activity;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.ExpandableListView;

import com.example.websocketchaifen.R;

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

public class ceshi extends AppCompatActivity {

    private ExpandableListView listView;
    private List<List<Item>> data = new ArrayList<>();
    private List<Item> mdata = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_ceshi);
        Item item = new Item();
        item.setName("A");
        item.setDetail("A");
        mdata.add(item);
        for (int i = 0; i < 4; i++) {
            data.add(mdata);
        }

        listView = (ExpandableListView) findViewById(R.id.expandableListView);
        myAdapter adapter = new myAdapter(this, data);
        listView.setAdapter(adapter);
        adapter.notifyDataSetChanged();
    }
}