Android 可折叠列表 示例

class ListAdapter

package cn.noybzy.explist;

import android.content.Context;
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 cn.noybzy.explist.bean.ListBean;
import cn.noybzy.explist.bean.User;
import cn.noybzy.login.R;


public class ListAdapter extends BaseExpandableListAdapter {
    private ArrayList<ListBean> list;
    private Context context;

    public ListAdapter(ArrayList<ListBean> list, Context context) {
        this.list = list;
        this.context = context;
    }

    @Override
    public int getGroupCount() {
        return list.size();
    }

    @Override
    public int getChildrenCount(int groupPosition) {
        return list.get(groupPosition).getUsers().size();
    }

    @Override
    public ListBean getGroup(int groupPosition) {
        return list.get(groupPosition);
    }

    @Override
    public User getChild(int groupPosition, int childPosition) {
        return list.get(groupPosition).getUsers().get(childPosition);
    }

    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

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

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

    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        GroupHolder groupHolder = null;
        if (convertView == null){
            convertView = View.inflate(context, R.layout.activity_expandable_listview_group_item,null);
            groupHolder = new GroupHolder();
            groupHolder.groupTitle = convertView.findViewById(R.id.group_title);
            groupHolder.groupOnline = convertView.findViewById(R.id.group_online);
            convertView.setTag(groupHolder);
        }else {
            groupHolder = (GroupHolder) convertView.getTag();
        }

        ListBean group = getGroup(groupPosition);
        groupHolder.groupTitle.setText(group.getGroupTitle());
        groupHolder.groupOnline.setText(group.getOnline() + "/" + group.getSum());


        return convertView;
    }

    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        ChildHolder childHolder = null;
        if (convertView == null){
            convertView = View.inflate(context, R.layout.activity_expandable_listview_child_item,null);
            childHolder = new ChildHolder();
            childHolder.pic = convertView.findViewById(R.id.pic);
            childHolder.username = convertView.findViewById(R.id.username);
            convertView.setTag(childHolder);
        }else {
            childHolder = (ChildHolder) convertView.getTag();
        }

        User child = getChild(groupPosition, childPosition);
//        childHolder.pic.setImageResource(1);
        childHolder.username.setText(child.getName());

        return convertView;
    }

    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return false;
    }

    class GroupHolder{
        private TextView groupTitle;
        private TextView groupOnline;

    }
    class ChildHolder{
        private ImageView pic;
        private TextView username;

    }
}

class DemoExpandableListView

package cn.noybzy.explist;

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

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import java.util.ArrayList;
import java.util.Random;

import cn.noybzy.explist.bean.ListBean;
import cn.noybzy.explist.bean.User;
import cn.noybzy.login.R;

public class DemoExpandableListView extends AppCompatActivity {
    private ExpandableListView listView;
    private ArrayList<ListBean> list;
    private static final int N = 100;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_expandable_listview);
        listView = findViewById(R.id.ExpandableListView);
        initData();
        listView.setAdapter(new ListAdapter(list,this));
    }

    private void initData(){
        Random random = new Random();
        list = new ArrayList<>();
        for (int i = 0; i < random.nextInt(N); i++) {
            ArrayList<User> users = new ArrayList<>();
            for (int j = 0; j < random.nextInt(N); j++) {
                users.add(new User("姓名","pic","在线","消息"));
            }
            ListBean listBean = new ListBean();
            listBean.setGroupTitle("分类");
            listBean.setSum(users.size());
            listBean.setOnline(random.nextInt(users.size()));
            listBean.setUsers(users);
            list.add(listBean);
        }
    }
}

class ListBean

package cn.noybzy.explist.bean;

import java.util.ArrayList;

public class ListBean {
    private String groupTitle;
    private int sum;
    private int online;
    private ArrayList<User> users;

    public ListBean() {
    }

    public void setGroupTitle(String groupTitle) {
        this.groupTitle = groupTitle;
    }

    public void setSum(int sum) {
        this.sum = sum;
    }

    public void setOnline(int online) {
        this.online = online;
    }

    public void setUsers(ArrayList<User> users) {
        this.users = users;
    }

    public String getGroupTitle() {
        return groupTitle;
    }

    public int getSum() {
        return sum;
    }

    public int getOnline() {
        return online;
    }

    public ArrayList<User> getUsers() {
        return users;
    }

    public ListBean(String groupTitle, int sum, int online, ArrayList<User> users) {
        this.groupTitle = groupTitle;
        this.sum = sum;
        this.online = online;
        this.users = users;
    }

    @Override
    public String toString() {
        return "ListBean{" +
                "groupTitle='" + groupTitle + '\'' +
                ", sum=" + sum +
                ", online=" + online +
                ", users=" + users +
                '}';
    }
}

class User

package cn.noybzy.explist.bean;

public class User {
    private String name;
    private String pic;
    private String onlineMeg;
    private String meg;

    public User(String name, String pic, String onlineMeg, String meg) {
        this.name = name;
        this.pic = pic;
        this.onlineMeg = onlineMeg;
        this.meg = meg;
    }

    public User() {
    }

    public String getName() {
        return name;
    }

    public String getPic() {
        return pic;
    }

    public String getOnlineMeg() {
        return onlineMeg;
    }

    public String getMeg() {
        return meg;
    }

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

    public void setPic(String pic) {
        this.pic = pic;
    }

    public void setOnlineMeg(String onlineMeg) {
        this.onlineMeg = onlineMeg;
    }

    public void setMeg(String meg) {
        this.meg = meg;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\'' +
                ", pic='" + pic + '\'' +
                ", onlineMeg='" + onlineMeg + '\'' +
                ", meg='" + meg + '\'' +
                '}';
    }
}