安卓二级列表 ExpandableListView

package text.htss.com.myapplication;

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

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

public class MainActivity extends AppCompatActivity {
private ExpandableListView expandableListView;
private List<String> group_list;
private List<List<String>> item_list;
private List<List<Integer>> item_list2;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

//测试数据
initDatas();

expandableListView = (ExpandableListView) findViewById(R.id.expendlist);
//设置默认只展示一组
expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
@Override
public void onGroupExpand(int groupPosition) {
for (int i = 0, count = expandableListView
.getExpandableListAdapter().getGroupCount(); i < count; i++) {
if (groupPosition != i) {// 关闭其他分组
expandableListView.collapseGroup(i);
}
}
}
});
expandableListView.setAdapter(new MyExpandableListViewAdapter(this));

//默认展开第一页（要在setAdapter后调用否则空指针）
expandableListView.expandGroup(0);

}

private void initDatas() {
group_list = new ArrayList<String>();
group_list.add("A");
group_list.add("B");
group_list.add("C");

item_list = new ArrayList<List<String>>();
item_list.add(group_list);
item_list.add(group_list);
item_list.add(group_list);

List<Integer> tmp_list = new ArrayList<Integer>();
tmp_list.add(R.mipmap.ic_launcher);
tmp_list.add(R.mipmap.ic_launcher);
tmp_list.add(R.mipmap.ic_launcher);

item_list2 = new ArrayList<List<Integer>>();
item_list2.add(tmp_list);
item_list2.add(tmp_list);
item_list2.add(tmp_list);
}

//用过ListView的人一定很熟悉，只不过这里是BaseExpandableListAdapter
class MyExpandableListViewAdapter extends BaseExpandableListAdapter {

private Context context;

public MyExpandableListViewAdapter(Context context) {
this.context = context;
}

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

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

@Override
public Object getGroup(int groupPosition) {
return group_list.get(groupPosition);
}

@Override
public Object getChild(int groupPosition, int childPosition) {
return item_list.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;
}

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
GroupHolder groupHolder = null;
if (convertView == null) {
convertView = (View) getLayoutInflater().from(context).inflate(
R.layout.expendlist_group, null);
groupHolder = new GroupHolder();
groupHolder.txt = (TextView) convertView.findViewById(R.id.txt);
// groupHolder.img = (ImageView) convertView
// .findViewById(R.id.img);
convertView.setTag(groupHolder);
} else {
groupHolder = (GroupHolder) convertView.getTag();
}
groupHolder.txt.setText(group_list.get(groupPosition));
return convertView;
}

@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
ItemHolder itemHolder = null;
if (convertView == null) {
convertView = (View) getLayoutInflater().from(context).inflate(
R.layout.expendlist_item, null);
itemHolder = new ItemHolder();
itemHolder.txt = (TextView) convertView.findViewById(R.id.txt);
itemHolder.img = (ImageView) convertView.findViewById(R.id.img);
convertView.setTag(itemHolder);
} else {
itemHolder = (ItemHolder) convertView.getTag();
}
itemHolder.txt.setText(item_list.get(groupPosition).get(
childPosition));
itemHolder.img.setBackgroundResource(item_list2.get(groupPosition).get(
childPosition));
return convertView;
}

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

}

class GroupHolder {
public TextView txt;
public ImageView img;
}

class ItemHolder {
public ImageView img;
public TextView txt;
}
}

<?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="10.0dp" >

<ImageView
android:id="@+id/img"
android:layout_width="20.0dp"
android:layout_height="20.0dp" />

<TextView
android:id="@+id/txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</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="wrap_content"
android:orientation="horizontal" >

<TextView
android:id="@+id/txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

<ImageView
android:id="@+id/img"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>