1.概述

ExpandableListView是可擴(kuò)展的二級(jí)下拉列表,繼承ListView

2.使用步驟

① 布局中定義ExpandableListView控件
② 初始化Group數(shù)據(jù),Child數(shù)據(jù)(ArrayList<ArrayList<Info>>)
③ 適配器BaseExpandaListAdapter
重寫10個(gè)方法 getGroupCount(),getGroup(),getGroupId(),getGroupView()
getChildCount(),getChild(),getChildId(),getChildView()
hasStablelds()行是否具有唯一id isChildSelectable() 子列表是否可點(diǎn)擊事件

3.屬性

divider 父類分割線
childDivider 子類分割線
dividerHeight 分割線高度
groupIndicator 控制父類前面的小箭頭
android:groupIndicator="@drawable/picture" 箭頭換照片
android:groupIndicator="@null" 去掉小箭頭
indicatorLeft 箭頭或者自己設(shè)置的圖片的右邊框距離手機(jī)左邊邊緣的距離,類似于marginLeft
indicatorStart 箭頭或者自己設(shè)置的圖片的左邊框距離手機(jī)左邊邊緣的距離,類似于marginLeft以上兩個(gè)屬性相結(jié)合可以使箭頭或自己設(shè)置的圖片變大變小或者翻轉(zhuǎn),因?yàn)榭刂屏思^或圖片的左右邊框
childIndicator 用于設(shè)置子項(xiàng)前顯示的圖標(biāo),不設(shè)置的話默認(rèn)是沒有圖標(biāo)的
//設(shè)置圖標(biāo)選擇
<item android:drawable=”@drawable/icon_t” android:state_expanded=”true”/>
<item android:drawable=”@drawable/icon_f” android:state_expanded=”false”/>

代碼

布局

<ExpandableListView
android:id="@+id/expand_lv"
android:layout_width="match_parent"
android:layout_height="match_parent"/>

要顯示的內(nèi)容

    //group數(shù)據(jù)
    private ArrayList<String> mGroupList;
    //item數(shù)據(jù)
    private ArrayList<ArrayList<String>> mItemSet;
    private void initData() {
        mGroupList = new ArrayList<>();
        mGroupList.add("我的家人");
        mGroupList.add("我的朋友");
        mGroupList.add("黑名單");

        mItemSet = new ArrayList<>();

        ArrayList<String> itemList1 = new ArrayList<>();
        itemList1.add("大妹");
        itemList1.add("二妹");
        itemList1.add("三妹");
        ArrayList<String> itemList2 = new ArrayList<>();
        itemList2.add("大美");
        itemList2.add("二美");
        itemList2.add("三美");
        ArrayList<String> itemList3 = new ArrayList<>();
        itemList3.add("狗蛋");
        itemList3.add("二丫");
        mItemSet.add(itemList1);
        mItemSet.add(itemList2);
        mItemSet.add(itemList3);
    }

子類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_centerVertical="true"
    android:padding="8dp"
    android:layout_height="wrap_content">

    <ImageView
        android:layout_marginLeft="40dp"
        android:src="@mipmap/ic_launcher"
        android:layout_width="40dp"
        android:layout_height="40dp" />
    <LinearLayout
        android:layout_marginLeft="12dp"
        android:orientation="vertical"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">
        <TextView
            android:id="@+id/tv_name"
            android:text="@string/app_name"
            android:textSize="16sp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TextView
            android:text="@string/app_name"
            android:textSize="16sp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </LinearLayout>
</LinearLayout>

4.自定義適配器，需要繼承 BaseExpandableListAdapter 抽象類，重寫相關(guān)的方法

public class MyAdapter extends BaseExpandableListAdapter {

    private Context mContext;
    private ArrayList<String> mGroup;
    private ArrayList<ArrayList<String>> mItemList;
    private final LayoutInflater mInflater;


    public MyAdapter(Context context, ArrayList<String> group, ArrayList<ArrayList<String>> itemList){
        this.mContext = context;
        this.mGroup = group;
        this.mItemList = itemList;
        mInflater = LayoutInflater.from(context);
    }

    //父項(xiàng)的個(gè)數(shù)
    @Override
    public int getGroupCount() {
        return mGroup.size();
    }

    //某個(gè)父項(xiàng)的子項(xiàng)的個(gè)數(shù)
    @Override
    public int getChildrenCount(int groupPosition) {
        return mItemList.get(groupPosition).size();
    }

    //獲得某個(gè)父項(xiàng)
    @Override
    public Object getGroup(int groupPosition) {
        return mGroup.get(groupPosition);
    }
    //獲得某個(gè)子項(xiàng)
    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return mItemList.get(groupPosition).get(childPosition);
    }

    //父項(xiàng)的Id
    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    //子項(xiàng)的id

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

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

    //獲取父項(xiàng)的view
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
        if (convertView == null){
            convertView = mInflater.inflate(R.layout.item_group,parent,false);
        }
        String group = mGroup.get(groupPosition);
        TextView tvGroup = (TextView) convertView.findViewById(R.id.tv_group);
        tvGroup.setText(group);
        return convertView;
    }

    //獲取子項(xiàng)的view
    @Override
    public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {
        final String child = mItemList.get(groupPosition).get(childPosition);
        if (convertView == null){
            convertView = mInflater.inflate(R.layout.item_item,parent,false);
        }

        TextView tvChild = (TextView)convertView.findViewById(R.id.tv_name);
        tvChild.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(mContext,child,Toast.LENGTH_SHORT).show();
            }
        });
        tvChild.setText(child);
        return convertView;

    }

    //子項(xiàng)是否可選中,如果要設(shè)置子項(xiàng)的點(diǎn)擊事件,需要返回true
    @Override
    public boolean isChildSelectable(int groupPosition, int childPosition) {
        return true;
    }
}

5.為 ExpandableListView 設(shè)置適配器

MyAdapter adapter = new MyAdapter(this, mGroupList, mItemSet);
mExpandableListView.setAdapter(adapter);
效果圖
[圖片上傳失敗...(image-a1caa2-1550577205126)]

監(jiān)聽事件

對(duì)于處理 Item 的點(diǎn)擊事件，還是要設(shè)置監(jiān)聽器，常用的有這幾類：
setOnChildClickListener//單擊子選項(xiàng)
setOnGroupClickListener//單擊組選項(xiàng)
setOnGroupCollapseListener//分組合并
setOnGroupExpandListener//分組合并