一、前言
“好记性不如烂笔头”，再次验证了这句话是真的很有道理啊，一个月前看了一下ExpandableListView的使用，今天再看居然忘了这个是干啥的了，今天就详细讲解一下ExpandableListView的使用方法，感觉对于二级条目显示功能都可以实现。
二、实现的功能
1、可实现二级列表条目显示功能，具体包括可自定义，父布局和子布局。可实现父布局全部展开和只展开一个功能。
三、具体代码
1、主xml代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:orientation="vertical"android:layout_height="match_parent"><include layout="@layout/top"/><ExpandableListViewandroid:id="@+id/expand_list_id"android:layout_width="match_parent"android:groupIndicator="@null"android:layout_height="match_parent"></ExpandableListView>
</LinearLayout>
2、父布局xml代码
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:background="@color/blue"android:layout_height="50dp"><TextViewandroid:id="@+id/parent_textview_id"android:layout_width="wrap_content"android:text="测试"android:textColor="@color/white"android:gravity="center_vertical"android:paddingLeft="10dp"android:textSize="18sp"android:layout_height="match_parent" /><ImageViewandroid:id="@+id/parent_image"android:layout_width="wrap_content"android:layout_alignParentRight="true"android:src="@drawable/img_arrow_right"android:layout_centerInParent="true"android:paddingRight="10dp"android:layout_height="wrap_content" /></RelativeLayout>
3、子布局xml代码
<?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"><TextViewandroid:id="@+id/chidren_item"android:layout_width="match_parent"android:text="子项目"android:gravity="center_vertical"android:paddingLeft="10dp"android:textColor="@color/black"android:layout_height="40dp" /></LinearLayout>
4、主activity代码
*** Created by fyf on 2019/3/1.* 描述：用于实现ExpandableListView的类，主要功能是实现二级列表条目显示*/
public class ExpandableListviewActivity extends BaseActivity {private ExpandableListView expand_list_id;//Model：定义的数据private String[] groups = {"开发部", "人力资源部", "销售部"};//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 = {{"赵珊珊", "钱丹丹", "孙可可", "李冬冬"}, {"周大福", "吴端口", "郑非", "王疯狂"}, {"冯程程", "陈类", "楚哦", "魏王"}};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.expandable_list_view);setTitle("ExpandableListView二级下拉",false,"");initView();}private void initView(){expand_list_id=findViewById(R.id.expand_list_id);ExpandableListviewAdapter adapter=new ExpandableListviewAdapter(this,groups,childs);expand_list_id.setAdapter(adapter);//默认展开第一个数组expand_list_id.expandGroup(0);//关闭数组某个数组，可以通过该属性来实现全部展开和只展开一个列表功能//expand_list_id.collapseGroup(0);expand_list_id.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {@Overridepublic boolean onGroupClick(ExpandableListView expandableListView, View view, int groupPosition, long l) {showToastShort(groups[groupPosition]);return false;}});//子视图的点击事件expand_list_id.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {@Overridepublic boolean onChildClick(ExpandableListView expandableListView, View view, int groupPosition, int childPosition, long l) {showToastShort(childs[groupPosition][childPosition]);return true;}});//用于当组项折叠时的通知。expand_list_id.setOnGroupCollapseListener(new ExpandableListView.OnGroupCollapseListener() {@Overridepublic void onGroupCollapse(int groupPosition) {showToastShort("折叠了数据___"+groups[groupPosition]);}});////用于当组项折叠时的通知。expand_list_id.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {@Overridepublic void onGroupExpand(int groupPosition) {showToastShort("展开了数据___"+groups[groupPosition]);}});}
}
5、adapter代码
/*** Created by fyf on 2019/3/1.* 描述：是二级显示列表的adapter*/
public class ExpandableListviewAdapter extends BaseExpandableListAdapter {//Model：定义的数据private String[] groups;//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;private Context context;public ExpandableListviewAdapter(Context context,String[] groups,String[][] childs){this.context=context;this.groups=groups;this.childs=childs;}@Overridepublic int getGroupCount() {return groups.length;}@Overridepublic int getChildrenCount(int i) {return childs[i].length;}@Overridepublic Object getGroup(int i) {return groups[i];}@Overridepublic Object getChild(int i, int i1) {return childs[i][i1];}@Overridepublic long getGroupId(int i) {return i;}@Overridepublic long getChildId(int i, int i1) {return i1;}@Override//分组和子选项是否持有稳定的ID, 就是说底层数据的改变会不会影响到它们public boolean hasStableIds() {return true;}@Override
/**** 获取显示指定组的视图对象** @param groupPosition 组位置* @param isExpanded 该组是展开状态还是伸缩状态，true=展开* @param convertView 重用已有的视图对象* @param parent 返回的视图对象始终依附于的视图组*/public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {GroupViewHolder groupViewHolder;if (convertView == null){convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.expand_parent_item,parent,false);groupViewHolder = new GroupViewHolder();groupViewHolder.parent_textview_id = convertView.findViewById(R.id.parent_textview_id);groupViewHolder.parent_image = convertView.findViewById(R.id.parent_image);convertView.setTag(groupViewHolder);}else {groupViewHolder = (GroupViewHolder)convertView.getTag();}groupViewHolder.parent_textview_id.setText(groups[groupPosition]);//如果是展开状态，if (isExpanded){groupViewHolder.parent_image.setImageDrawable(ContextCompat.getDrawable(context,R.drawable.img_arrow_down));}else{groupViewHolder.parent_image.setImageDrawable(ContextCompat.getDrawable(context,R.drawable.img_arrow_right));}return convertView;}@Overridepublic View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView, ViewGroup parent) {ChildViewHolder childViewHolder;if (convertView==null){convertView = LayoutInflater.from(parent.getContext()).inflate(R.layout.expand_chidren_item,parent,false);childViewHolder = new ChildViewHolder();childViewHolder.chidren_item = (TextView)convertView.findViewById(R.id.chidren_item);convertView.setTag(childViewHolder);}else {childViewHolder = (ChildViewHolder) convertView.getTag();}childViewHolder.chidren_item.setText(childs[groupPosition][childPosition]);return convertView;}//指定位置上的子元素是否可选中@Overridepublic boolean isChildSelectable(int i, int i1) {return true;}static class GroupViewHolder {TextView parent_textview_id;ImageView parent_image;}static class ChildViewHolder {TextView chidren_item;}
}
