前言
眼下回到了工作岗位，第一件事情就是ExpandListView的优化。这里简单的用一个Demo介绍一下ExpandableListView的使用。
简介一下Demo实现的功能，主要是继承BaseExpandableListAdapter来自己定义adapter呈现ExpandableListView数据：
- 每一个child item有一个TextView和一个ImageView删除标识。
- 当点击一个child item，弹出Toast提示。
- child item能够通过点击删除图标来删除。
- 每次展开特定group时。其它group自己主动收缩。
Demo效果展示：
Android实现
创建一个新的Android项目，我将其命名为expandtutorial。
XML布局文件
expandtutorial项目总共须要三个xml布局文件。各自是activity_main.xml。 child_item.xml。 group_item.xml。
activity_main.xml
这个是用来布局ExpandableListView的，内容例如以下：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ExpandableListView
android:id="@+id/expandable_list_view_id"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</ExpandableListView>
</RelativeLayout>group_item.xml
这是用来定义父列表的样式，由一个TextView和一个ImageView构成
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="#ffffff"
android:orientation="horizontal"
android:gravity="center_vertical">
<TextView
android:id="@+id/group_text"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_marginLeft="16dp"
android:textColor="#808080"
android:textSize="16sp"
android:gravity="center_vertical"
android:layout_alignParentLeft="true"
android:text="@string/app_name"/>
<ImageView
android:id="@+id/group_indicator"
android:src="@drawable/ic_guide_listview_down"
android:contentDescription="@null"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_marginRight="16sp"
android:layout_alignParentRight="true"/>
</RelativeLayout>
child_item.xml
这是用来定义孩子列表的样式
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/child_item_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp" >
<TextView
android:id="@+id/child_item"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:paddingLeft="25dp" />
<ImageView
android:id="@+id/child_delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:contentDescription="@null"
android:src="@drawable/delete" />
</RelativeLayout>自己定义Adapter
自己定义adapter是继承自BaseExpandableListAdapter。有几个须要注意的地方：
- 使用静态内部类标识父item和子item的weidget，由于这些控件的id是同样的，这样能够节省掉每次findViewById的时间。
- 重写（override）isChildSelectable方法，返回true，表示子item是能够点击的。
package com.example.expandtutorial;
import java.util.ArrayList;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.graphics.Typeface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class CustomerAdapter extends BaseExpandableListAdapter{
private ArrayList<ParentObj> datas;
private Context context;
public CustomerAdapter(ArrayList<ParentObj> datas, Context context) {
super();
this.datas = datas;
this.context = context;
}
@Override
public int getGroupCount() {
return datas.size();
}
@Override
public int getChildrenCount(int groupPosition) {
return datas.get(groupPosition).getChilds().size();
}
@Override
public Object getGroup(int groupPosition) {
return datas.get(groupPosition);
}
@Override
public Object getChild(int groupPosition, int childPosition) {
return datas.get(groupPosition).getChilds().get(childPosition);
}
@Override
public long getGroupId(int groupPosition) {
return groupPosition;
}
@Override
public long getChildId(int groupPosition, int childPosition) {
return childPosition;
}
@Override
// 是否有稳定的id。跟刷新顺序有关
public boolean hasStableIds() {
return false;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent) {
ParentViewHolder pviewHolder;
if (convertView == null) {
convertView = LayoutInflater.from(context).inflate(R.layout.group_item, parent, false);
pviewHolder = new ParentViewHolder();
pviewHolder.pTextView = (TextView) convertView.findViewById(R.id.group_text);
pviewHolder.pImageView = (ImageView) convertView.findViewById(R.id.group_indicator);
convertView.setTag(pviewHolder);
}
pviewHolder = (ParentViewHolder)convertView.getTag();
pviewHolder.pTextView.setTypeface(null, Typeface.BOLD);
pviewHolder.pTextView.setText(datas.get(groupPosition).getpName());
if (isExpanded) {
pviewHolder.pImageView.setImageResource(R.drawable.ic_guide_listview_up);
} else {
pviewHolder.pImageView.setImageResource(R.drawable.ic_guide_listview_down);
}
return convertView;
}
@Override
public View getChildView(int groupPosition, int childPosition, boolean isLastChild, View convertView,
ViewGroup parent) {
ChildViewHolder cViewHolder;
if (convertView == null) {
convertView = LayoutInflater.from(context).inflate(R.layout.child_item, parent, false);
cViewHolder = new ChildViewHolder();
cViewHolder.cTextView = (TextView)convertView.findViewById(R.id.child_item);
cViewHolder.cImageView = (ImageView) convertView.findViewById(R.id.child_delete);
convertView.setTag(cViewHolder);
}
cViewHolder = (ChildViewHolder)convertView.getTag();
cViewHolder.cTextView.setText(datas.get(groupPosition).getChilds().get(childPosition).getcName());
final int gPosition = groupPosition;
final int cPosition = childPosition;
cViewHolder.cImageView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setMessage("Do you want to remove?");
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
datas.get(gPosition).getChilds().remove(cPosition);
notifyDataSetChanged();
}
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.cancel();
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
});
return convertView;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
return true;
}
static class ParentViewHolder {
TextView pTextView;
ImageView pImageView;
}
static class ChildViewHolder {
TextView cTextView;
ImageView cImageView;
}
}
Activity
我们的主Activity，用来呈现UI效果，这里主要有两个地方须要注意：
- ExpandableListView须要和自己定义adapter进行绑定，通过setAdapter方法。
- 默认ExpandableListView带了一个指示箭头。我们自己定义布局是不须要这个指示箭头的。能够使用expandableListView.setGroupIndicator(null);方法将其去掉。
- 设置setOnGroupExpandListener，当展开一个特定的group时，关闭其它group。
- 设置setOnChildClickListener，监听孩子点击事件。
package com.example.expandtutorial;
import java.util.ArrayList;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.ExpandableListView.OnGroupExpandListener;
import android.widget.Toast;
public class MainActivity extends Activity {
private ExpandableListView expandableListView;
private CustomerAdapter customerAdapter;
private ArrayList<ParentObj> listData = new ArrayList<ParentObj>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
createGroupData();
createChildData();
expandableListView = (ExpandableListView) findViewById(R.id.expandable_list_view_id);
customerAdapter = new CustomerAdapter(listData, this);
expandableListView.setAdapter(customerAdapter);
expandableListView.setGroupIndicator(null);
expandableListView.setOnGroupExpandListener(new OnGroupExpandListener() {
@Override
public void onGroupExpand(int groupPosition) {
for (int i = 0; i < customerAdapter.getGroupCount(); i ++) {
if (i != groupPosition) {
expandableListView.collapseGroup(i);
}
}
}
});
expandableListView.setOnChildClickListener(new OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
Toast.makeText(MainActivity.this, listData.get(groupPosition).getChilds().get(childPosition).getcName(), Toast.LENGTH_LONG).show();
return true;
}
});
}
private void createGroupData() {
ParentObj p1 = new ParentObj();
p1.setpName("HP");
listData.add(p1);
ParentObj p2 = new ParentObj();
p2.setpName("DELL");
listData.add(p2);
ParentObj p3 = new ParentObj();
p3.setpName("Lenovo");
listData.add(p3);
ParentObj p4 = new ParentObj();
p4.setpName("Sony");
listData.add(p4);
ParentObj p5 = new ParentObj();
p5.setpName("HCL");
listData.add(p5);
ParentObj p6 = new ParentObj();
p6.setpName("Samsung");
listData.add(p6);
}
private void createChildData() {
// preparing laptops collection(child)
String[] hpModels = { "HP Pavilion G6-2014TX", "ProBook HP 4540", "HP Envy 4-1025TX" };
String[] hclModels = { "HCL S2101", "HCL L2102", "HCL V2002" };
String[] lenovoModels = { "IdeaPad Z Series", "Essential G Series", "ThinkPad X Series", "Ideapad Z Series" };
String[] sonyModels = { "VAIO E Series", "VAIO Z Series", "VAIO S Series", "VAIO YB Series" };
String[] dellModels = { "Inspiron", "Vostro", "XPS" };
String[] samsungModels = { "NP Series", "Series 5", "SF Series" };
for (ParentObj p : listData) {
if (p.getpName().equals("HP")) {
ArrayList<ChildObj> clists = new ArrayList<ChildObj>();
for (int i = 0; i < hpModels.length; i ++) {
ChildObj cObj = new ChildObj();
cObj.setcName(hpModels[i]);
clists.add(cObj);
}
p.setChilds(clists);
} else if (p.getpName().equals("DELL")) {
ArrayList<ChildObj> clists = new ArrayList<ChildObj>();
for (int i = 0; i < dellModels.length; i ++) {
ChildObj cObj = new ChildObj();
cObj.setcName(dellModels[i]);
clists.add(cObj);
}
p.setChilds(clists);
} else if (p.getpName().equals("Lenovo")) {
ArrayList<ChildObj> clists = new ArrayList<ChildObj>();
for (int i = 0; i < lenovoModels.length; i ++) {
ChildObj cObj = new ChildObj();
cObj.setcName(lenovoModels[i]);
clists.add(cObj);
}
p.setChilds(clists);
} else if (p.getpName().equals("Sony")) {
ArrayList<ChildObj> clists = new ArrayList<ChildObj>();
for (int i = 0; i < sonyModels.length; i ++) {
ChildObj cObj = new ChildObj();
cObj.setcName(sonyModels[i]);
clists.add(cObj);
}
p.setChilds(clists);
} else if (p.getpName().equals("HCL")) {
ArrayList<ChildObj> clists = new ArrayList<ChildObj>();
for (int i = 0; i < hclModels.length; i ++) {
ChildObj cObj = new ChildObj();
cObj.setcName(hclModels[i]);
clists.add(cObj);
}
p.setChilds(clists);
} else {
ArrayList<ChildObj> clists = new ArrayList<ChildObj>();
for (int i = 0; i < samsungModels.length; i ++) {
ChildObj cObj = new ChildObj();
cObj.setcName(samsungModels[i]);
clists.add(cObj);
}
p.setChilds(clists);
}
}
}
}
class ParentObj {
private String pName;
private ArrayList<ChildObj> childs = new ArrayList<ChildObj>();
public String getpName() {
return pName;
}
public void setpName(String pName) {
this.pName = pName;
}
public ArrayList<ChildObj> getChilds() {
return childs;
}
public void setChilds(ArrayList<ChildObj> childs) {
this.childs.clear();
this.childs.addAll(childs);
}
}
class ChildObj {
private String cName;
public String getcName() {
return cName;
}
public void setcName(String cName) {
this.cName = cName;
}
}源代码
我将源代码上传到CSDN，大家能够免费下载，欢迎跟帖讨论。源代码地址：http://download.csdn.net/detail/zinss26914/7532205
来源：https://www.cnblogs.com/clnchanpin/p/7095710.html