Android: ExpandableListView implements drop-down secondary list

Source: rookie tutorial, the following is the direct download address

The following is an implementation case

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I haven't figured it out yet, but copying the source code did achieve the address of the rookie tutorial. Keep a backup record for yourself, xdm, red~~

https://www.runoob.com/w3cnote/android-tutorial-expandablelistview.html

1. Layout three files

1.1，item_exlist_item.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="horizontal"
    android:padding="5dp"
    android:background="#6BBA79">

    <ImageView
        android:id="@+id/img_icon"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:src="@mipmap/iv_lol_icon1"
        android:focusable="false"/>

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:layout_marginTop="15dp"
        android:focusable="false"
        android:text="提莫"
        android:textSize="18sp" />

</LinearLayout>

1.2，item_exlist_group.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="horizontal"
    android:padding="5dp">

    <TextView
        android:id="@+id/tv_group_name"
        android:layout_width="match_parent"
        android:layout_height="56dp"
        android:gravity="center_vertical"
        android:paddingLeft="30dp"
        android:text="AP"
        android:textStyle="bold"
        android:textSize="20sp" />

</LinearLayout>

1.3，activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="5dp"
    tools:context=".MainActivity">

    <ExpandableListView
        android:id="@+id/exlist_lol"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:childDivider="#E02D2F"/>

</RelativeLayout>

2. 4 files of logic code

2.1，Group.java

package jay.com.expandablelistviewdemo;

/**
 * Created by Jay on 2015/9/25 0025.
 */
public class Group {
    private String gName;

    public Group() {
    }

    public Group(String gName) {
        this.gName = gName;
    }

    public String getgName() {
        return gName;
    }

    public void setgName(String gName) {
        this.gName = gName;
    }
}

2.2，Item.java

package jay.com.expandablelistviewdemo;

/**
 * Created by Jay on 2015/9/25 0025.
 */
public class Item {

    private int iId;
    private String iName;

    public Item() {
    }

    public Item(int iId, String iName) {
        this.iId = iId;
        this.iName = iName;
    }

    public int getiId() {
        return iId;
    }

    public String getiName() {
        return iName;
    }

    public void setiId(int iId) {
        this.iId = iId;
    }

    public void setiName(String iName) {
        this.iName = iName;
    }
}

2.3，MainActivity.java

package jay.com.expandablelistviewdemo;

import android.content.Context;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    private ArrayList<Group> gData = null;
    private ArrayList<ArrayList<Item>> iData = null;
    private ArrayList<Item> lData = null;
    private Context mContext;
    private ExpandableListView exlist_lol;
    private MyBaseExpandableListAdapter myAdapter = null;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = MainActivity.this;
        exlist_lol = (ExpandableListView) findViewById(R.id.exlist_lol);


        //数据准备
        gData = new ArrayList<Group>();
        iData = new ArrayList<ArrayList<Item>>();
        gData.add(new Group("AD"));
        gData.add(new Group("AP"));
        gData.add(new Group("TANK"));

        lData = new ArrayList<Item>();

        //AD组
        lData.add(new Item(R.mipmap.iv_lol_icon3,"剑圣"));
        lData.add(new Item(R.mipmap.iv_lol_icon4,"德莱文"));
        lData.add(new Item(R.mipmap.iv_lol_icon13,"男枪"));
        lData.add(new Item(R.mipmap.iv_lol_icon14,"韦鲁斯"));
        iData.add(lData);
        //AP组
        lData = new ArrayList<Item>();
        lData.add(new Item(R.mipmap.iv_lol_icon1, "提莫"));
        lData.add(new Item(R.mipmap.iv_lol_icon7, "安妮"));
        lData.add(new Item(R.mipmap.iv_lol_icon8, "天使"));
        lData.add(new Item(R.mipmap.iv_lol_icon9, "泽拉斯"));
        lData.add(new Item(R.mipmap.iv_lol_icon11, "狐狸"));
        iData.add(lData);
        //TANK组
        lData = new ArrayList<Item>();
        lData.add(new Item(R.mipmap.iv_lol_icon2, "诺手"));
        lData.add(new Item(R.mipmap.iv_lol_icon5, "德邦"));
        lData.add(new Item(R.mipmap.iv_lol_icon6, "奥拉夫"));
        lData.add(new Item(R.mipmap.iv_lol_icon10, "龙女"));
        lData.add(new Item(R.mipmap.iv_lol_icon12, "狗熊"));
        iData.add(lData);

        myAdapter = new MyBaseExpandableListAdapter(gData,iData,mContext);
        exlist_lol.setAdapter(myAdapter);


        //为列表设置点击事件
        exlist_lol.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                Toast.makeText(mContext, "你点击了：" + iData.get(groupPosition).get(childPosition).getiName(), Toast.LENGTH_SHORT).show();
                return true;
            }
        });


    }
}

2.4，MyBaseExpandableListAdapter.java

package jay.com.expandablelistviewdemo;

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 java.util.ArrayList;

/**
 * Created by Jay on 2015/9/25 0025.
 */
public class MyBaseExpandableListAdapter extends BaseExpandableListAdapter {

    private ArrayList<Group> gData;
    private ArrayList<ArrayList<Item>> iData;
    private Context mContext;

    public MyBaseExpandableListAdapter(ArrayList<Group> gData,ArrayList<ArrayList<Item>> iData, Context mContext) {
        this.gData = gData;
        this.iData = iData;
        this.mContext = mContext;
    }

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

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

    @Override
    public Group getGroup(int groupPosition) {
        return gData.get(groupPosition);
    }

    @Override
    public Item getChild(int groupPosition, int childPosition) {
        return iData.get(groupPosition).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;
    }

    //取得用于显示给定分组的视图. 这个方法仅返回分组的视图对象
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

        ViewHolderGroup groupHolder;
        if(convertView == null){
            convertView = LayoutInflater.from(mContext).inflate(
                    R.layout.item_exlist_group, parent, false);
            groupHolder = new ViewHolderGroup();
            groupHolder.tv_group_name = (TextView) convertView.findViewById(R.id.tv_group_name);
            convertView.setTag(groupHolder);
        }else{
            groupHolder = (ViewHolderGroup) convertView.getTag();
        }
        groupHolder.tv_group_name.setText(gData.get(groupPosition).getgName());
        return convertView;
    }

    //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) {
        ViewHolderItem itemHolder;
        if(convertView == null){
            convertView = LayoutInflater.from(mContext).inflate(
                    R.layout.item_exlist_item, parent, false);
            itemHolder = new ViewHolderItem();
            itemHolder.img_icon = (ImageView) convertView.findViewById(R.id.img_icon);
            itemHolder.tv_name = (TextView) convertView.findViewById(R.id.tv_name);
            convertView.setTag(itemHolder);
        }else{
            itemHolder = (ViewHolderItem) convertView.getTag();
        }
        itemHolder.img_icon.setImageResource(iData.get(groupPosition).get(childPosition).getiId());
        itemHolder.tv_name.setText(iData.get(groupPosition).get(childPosition).getiName());
        return convertView;
    }

    //设置子列表是否可选中
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }


    private static class ViewHolderGroup{
        private TextView tv_group_name;
    }

    private static class ViewHolderItem{
        private ImageView img_icon;
        private TextView tv_name;
    }

}

So much content after it's done