ExpandableListView葵诈，就是可折疊的列表，它是ListView的子類麸俘， 在ListView的基礎(chǔ)上它把應(yīng)用中的列表項(xiàng)分為幾組齐板，每組里又可包含多個(gè)列表項(xiàng)吵瞻。

ExpandableListView用法和Listview差不多葛菇，設(shè)置適配器，適配器里面設(shè)置數(shù)據(jù)橡羞。

1.我們先在控制器的布局文件中添加一個(gè)ExpandableListView

<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/exlistview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:childDivider="#E02D2F"/>

</RelativeLayout>

2.ExpandableListView中分為組頭和組里的每一個(gè)item眯停，所以需要兩個(gè)布局文件，相互對(duì)應(yīng)卿泽。
設(shè)置組頭的布局文件group_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">

    <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="組頭"
        android:textStyle="bold"
        android:textSize="20sp" />

</LinearLayout>

設(shè)置每一組的item布局文件list_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">

    <ImageView
        android:id="@+id/img_icon"
        android:layout_width="48dp"
        android:layout_height="48dp"
        android:src="@mipmap/ic_launcher"
        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="每一組"
        android:textSize="18sp" />
    
</LinearLayout>

回到控制器中
獲取到ExpandableListView

        expandableListView = (ExpandableListView) findViewById(R.id.exlistview);

設(shè)置適配器

         expandableListView.setAdapter(new MyExpandableListView());// 設(shè)置適配器

自定義適配器

//為ExpandableListView自定義適配器
    class MyExpandableListView extends BaseExpandableListAdapter {

        //返回一級(jí)列表的個(gè)數(shù)
        @Override
        public int getGroupCount() {
            return groups.length;
        }

        //返回每個(gè)二級(jí)列表的個(gè)數(shù)
        @Override
        public int getChildrenCount(int groupPosition) { //參數(shù)groupPosition表示第幾個(gè)一級(jí)列表
            ArrayList list = childs.get(groupPosition);
            return list.size();
//            return childs[groupPosition].length;
        }

        //返回一級(jí)列表的單個(gè)item（返回的是對(duì)象）
        @Override
        public Object getGroup(int groupPosition) {
            return groups[groupPosition];
        }

        //返回二級(jí)列表中的單個(gè)item（返回的是對(duì)象）
        @Override
        public Object getChild(int groupPosition, int childPosition) {
//            return childs[groupPosition][childPosition];  //不要誤寫成groups[groupPosition][childPosition]
            ArrayList list = childs.get(groupPosition);
            return list.get(childPosition);
        }

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

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

        //每個(gè)item的id是否是固定莺债？一般為true
        @Override
        public boolean hasStableIds() {
            return true;
        }

        //【重要】填充一級(jí)列表
        @Override
        public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {

            if (convertView == null) {
                convertView = getLayoutInflater().inflate(R.layout.group_item, null);
            } else {

            }
            TextView tv_group = (TextView) convertView.findViewById(R.id.tv_group_name);
            tv_group.setText(groups[groupPosition]);
            return convertView;
        }

        //【重要】填充二級(jí)列表
        @Override
        public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {

            if (convertView == null) {
                convertView = getLayoutInflater().inflate(R.layout.list_item, null);
            }

            ImageView iv_child = (ImageView) convertView.findViewById(R.id.img_icon);
            TextView tv_child = (TextView) convertView.findViewById(R.id.tv_name);

            ArrayList list = childs.get(groupPosition);
            ItemModel model = (ItemModel)list.get(childPosition);
            iv_child.setImageResource(model.getiId());
            tv_child.setText(model.getiName());

//            tv_child.setText(childs[groupPosition][childPosition]);

            return convertView;
        }

        //二級(jí)列表中的item是否能夠被選中？
        @Override
        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }
    }

設(shè)置每一組是否展開：.expandGroup()
全部展開：

for (int i = 0;i<groups.length;
    expandableListView.expandGroup(i);// 設(shè)置展開
}

// 設(shè)置組頭箭頭為空

expandableListView.setGroupIndicator(null);

完整Demo