ExpandableListView 二级列表

package com.example.administrator.expland;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

private ExpandableListView expandListview;
private String[] groups = {"A", "B", "C", "D", "E"};
//注意，字符数组不要写成{{"A1,A2,A3,A4"}, {"B1,B2,B3,B4，B5"}, {"C1,C2,C3,C4"}}*/
private String[][] childs = {{"A1", "A2", "A3", "A4"}, {"A1", "A2", "A3", "B4"}, {"A1", "A2", "A3", "C4"}, {"A1", "A2", "A3", "C4"}, {"A1", "A2", "A3", "C4"}};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
expandListview = (ExpandableListView) findViewById(R.id.expandListview);
expandListview.setAdapter(new MyExpandableListView());
}

//为ExpandableListView自定义适配器
class MyExpandableListView extends BaseExpandableListAdapter {

//返回一级列表的个数
@Override
public int getGroupCount() {
return groups.length;
}

//返回每个二级列表的个数
@Override
public int getChildrenCount(int groupPosition) { //参数groupPosition表示第几个一级列表
return childs[groupPosition].length;
}

//返回一级列表的单个item（返回的是对象）
@Override
public Object getGroup(int groupPosition) {
return groups[groupPosition];
}

@Override
public Object getChild(int groupPosition, int childPosition) {
return childs[groupPosition][childPosition];
}

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

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

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

@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
GroupViewHolder groupViewHolder;
if (convertView == null) {
convertView = LayoutInflater.from(MainActivity.this).inflate(R.layout.item_group, parent, false);
groupViewHolder = new GroupViewHolder();
groupViewHo
4000
lder.tvTitle = (TextView) convertView.findViewById(R.id.tv_group);
convertView.setTag(groupViewHolder);
} else {
groupViewHolder = (GroupViewHolder) convertView.getTag();
}
groupViewHolder.tvTitle.setText(groups[groupPosition]);
return convertView;
}

@Override
public View getChildView(int groupPosition, int childPosition, boolean b, View convertView, ViewGroup parent) {
ChildViewHolder childViewHolder;
if (convertView == null) {
convertView = LayoutInflater.from(MainActivity.this).inflate(R.layout.item_child, parent, false);
childViewHolder = new ChildViewHolder();
childViewHolder.tvTitle = (TextView) convertView.findViewById(R.id.tv_child);
convertView.setTag(childViewHolder);
} else {
childViewHolder = (ChildViewHolder) convertView.getTag();
}
childViewHolder.tvTitle.setText(childs[groupPosition][childPosition]);
return convertView;
}

@Override
public boolean isChildSelectable(int i, int i1) {
return true;
}

}

static class GroupViewHolder {
TextView tvTitle;
}

static class ChildViewHolder {
TextView tvTitle;
}
}

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="com.example.administrator.expland.MainActivity">

<ExpandableListView
android:id="@+id/expandListview"
android:layout_width="690px"
android:layout_height="544px"></ExpandableListView>

</android.support.constraint.ConstraintLayout>

<?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">
<TextView
android:id="@+id/tv_group"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:gravity="center"
android:text="group text"
android:layout_marginLeft="50dp"
/>
</LinearLayout>

<?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">

<ImageView
android:id="@+id/iv_child"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginLeft="50dp"
android:src="@mipmap/ic_launcher" />

<TextView
android:id="@+id/tv_child"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="item text" />
</LinearLayout>