android系统控件ExpandableListView默认显示效果的实现：
效果图见这个链接:系统默认显示效果
主页面：
package www.yalong.com.expandablelistview;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
public class MainActivity extends AppCompatActivity {
ExpandableListView expanList;
ExpandableListAdapter myExpanListAdapter;
String[] groups =new String[]{"生活基本", "生活拓展", "其他"};
String[][] childs =new String[][]{{"衣", "食", "住", "行"}, {"吃", "喝", "玩", "乐"}, {"读书", "写字"}};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView() {
expanList = findViewById(R.id.expand_list);
myExpanListAdapter =new MyExpandableListAdapter(MainActivity.this, groups, childs);
expanList.setAdapter(myExpanListAdapter);
// expanList.setGroupIndicator(null);//隐藏系统默认的左边的向下小图标
}
}
适配器类：
package www.yalong.com.expandablelistview;
import android.content.Context;
import android.database.DataSetObserver;
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.zip.Inflater;
/**
* Created by Administrator on 2020/5/19 0019.
*/
public class MyExpandableListAdapter extends BaseExpandableListAdapter {
private Contextcontext;
private String[]groups;
private String[][]childs;
public MyExpandableListAdapter(Context context,String[] groups, String[][] childs) {
this.context = context;
this.groups = groups;
this.childs = childs;
}
@Override
public int getGroupCount() {
return groups.length;
}
@Override
public int getChildrenCount(int i) {
return childs[i].length;
}
@Override
public ObjectgetGroup(int i) {
return groups[i];
}
@Override
public ObjectgetChild(int i, int i1) {
return childs[i][i1];
}
@Override
public long getGroupId(int i) {
return i;
}
@Override
public long getChildId(int i, int i1) {
return i1;
}
@Override
public boolean hasStableIds() {
return true;
}
@Override
public ViewgetGroupView(int i, boolean b, View view, ViewGroup viewGroup) {
GroupViewHolder groupViewHolder;
if (view ==null) {
view = LayoutInflater.from(context).inflate(R.layout.layout_groups, viewGroup, false);
groupViewHolder =new GroupViewHolder();
groupViewHolder.imageView=view.findViewById(R.id.parent_img);
groupViewHolder.textView = view.findViewById(R.id.parent_txt);
view.setTag(groupViewHolder);
}else {
groupViewHolder = (GroupViewHolder) view.getTag();
}
groupViewHolder.textView.setText(groups[i]);
//以下注释掉了代码可以实现ExpandableListView展开/折叠两种状态不同的图片显示
// if (b){
//
// groupViewHolder.imageView.setImageResource(R.drawable.icon_arrow_up);
//
//
//
// }else {
//
// groupViewHolder.imageView.setImageResource(R.drawable.icon_arrow_right);
//
//
// }
return view;
}
@Override
public ViewgetChildView(int i, int i1, boolean b, View view, ViewGroup viewGroup) {
//b 为true ：选中
ChildViewHolder childViewHolder;
if (view ==null) {
view = LayoutInflater.from(context).inflate(R.layout.layout_childs, viewGroup, false);
childViewHolder =new ChildViewHolder();
childViewHolder.textView = view.findViewById(R.id.child_txt);
view.setTag(childViewHolder);
}else {
childViewHolder = (ChildViewHolder) view.getTag();
}
childViewHolder.textView.setText(childs[i][i1]);
return view;
}
@Override
public boolean isChildSelectable(int i, int i1) {
return true;
}
static class GroupViewHolder {
ImageView imageView;
TextView textView;
}
static class ChildViewHolder {
TextView textView;
}
}
xml文件：
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
tools:context="www.yalong.com.expandablelistview.MainActivity">
<ExpandableListView
android:id="@+id/expand_list"
android:childDivider="@color/colorPrimaryDark"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
layout_groups.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">
<LinearLayout
android:layout_marginTop="10dp"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical">
<TextView
android:id="@+id/parent_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="start"
android:paddingLeft="100dp"
android:textColor="@color/colorAccent"
android:textSize="20sp" />
<android.support.v4.widget.Space
android:layout_width="0dp"
android:layout_height="1dp"
android:layout_weight="1"
/>
<ImageView
android:id="@+id/parent_img"
android:layout_width="30dp"
android:layout_height="30dp"
android:layout_marginLeft="20dp"
android:layout_marginRight="40dp"
/>
</LinearLayout>
</LinearLayout>
layout_childs.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">
<TextView
android:id="@+id/child_txt"
android:textColor="@color/colorPrimary"
android:textSize="15sp"
android:gravity="start"
android:paddingLeft="100dp"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
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