android开发步步为营之5：ExpandableListView模拟QQ好友列表

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ExpandableListView可展开的列表视图，本文我们要学习的是，如何使用这个控件，实现QQ好友列表这样的效果。

一、先学习理论知识

public class

ExpandableListView

extends ListView

java.lang.Object

android.view.View

android.view.ViewGroup

android.widget.AdapterView<T extends android.widget.Adapter>

android.widget.AbsListView

android.widget.ListView

android.widget.ExpandableListView

ClassOverview

Aview that shows items in a vertically scrolling two-level list. This differsfrom the ListViewby allowing two levels: groups which can individually be expanded to show itschildren. The items come from the ExpandableListAdapterassociated with this view.

Expandablelists are able to show an indicator beside each item to display the item'scurrent state (the states are usually one of expanded group, collapsed group,child, or last child). Use setChildIndicator(Drawable) or setGroupIndicator(Drawable) (or the corresponding XML attributes) to set these indicators (see thedocs for each method to see additional state that each Drawable can have). Thedefault style for anExpandableListViewprovides indicators which will be shown next to Views given to the ExpandableListView.The layouts android.R.layout.simple_expandable_list_item_1 andandroid.R.layout.simple_expandable_list_item_2 (which should be used withSimpleCursorTreeAdapter) contain the preferred position information for indicators.

Thecontext menu information set by an ExpandableListViewwill be a ExpandableListView.ExpandableListContextMenuInfo object withpackedPositionbeing a packed position that can be used with getPackedPositionType(long) and the other similar methods.

Note: You cannot usethe value wrap_contentfor the android:layout_height attribute of a ExpandableListView in XML if the parent's size is also notstrictly specified (for example, if the parent were ScrollView you could notspecify wrap_content since it also can be any length. However, you can usewrap_content if the ExpandableListView parent has a specific size, such as 100pixels.

二、实践

第一步设计页面

因为我们继承了ExpandableList，所以我们不必要另外再设计一个程序界面，如果只是继承了Activity，那就必须设计一个页面，里面放上android:id="@+id/android:list"的ExpandableListView。这里我们用到了自定义的子项目页面视图evchildview.xml

<?xml version="1.0"encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

</RelativeLayout>

第二步、设计Activity ExpandableListViewTest

/**

* ExpandableListView example

package com.figo.helloworld;

import android.app.ExpandableListActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.ExpandableListView;

import android.widget.TextView;

import android.widget.Toast;

/**

* @author zhuzhifei

public class ExpandableListViewTest extends ExpandableListActivity {

private ExpandableListView expandableListView;

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generatedmethod stub

super.onCreate(savedInstanceState);

//如果没有继承ExpandableListActivity采用方法一

//setContentView(R.layout.expandablelistviewtest);

//expandableListView=(ExpandableListView)findViewById(R.id.expandableListView1);

//expandableListView.setAdapter(expandableListAdapterTest);

//继承了ExpandableListActivity采用方法二

ExpandableListAdapterTest expandableListAdapterTest = newExpandableListAdapterTest(

ExpandableListViewTest.this);

setListAdapter(expandableListAdapterTest);

}

/**

* 点击子项时，触发点击事件

@Override

public boolean onChildClick(ExpandableListView parent, View v,

int groupPosition, int childPosition, long id) {

TextView tvName = (TextView) v.findViewById(R.id.tvName);

Toast.makeText(ExpandableListViewTest.this, "name:" + tvName.getText(),

Toast.LENGTH_LONG).show();

return super.onChildClick(parent, v, groupPosition, childPosition,id);

}

/**

* 组合拢事件

@Override

public void onGroupCollapse(int groupPosition) {

// TODO Auto-generatedmethod stub

super.onGroupCollapse(groupPosition);

}

/**

* 组展开事件

@Override

public void onGroupExpand(int groupPosition) {

// TODO Auto-generatedmethod stub

super.onGroupExpand(groupPosition);

}

第三步、设计ExpandableListView的Adapter

/**

* ExpandableListView数据适配器

package com.figo.helloworld;

import android.content.Context;

import android.view.Gravity;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AbsListView;

import android.widget.BaseExpandableListAdapter;

import android.widget.ImageView;

import android.widget.TextView;

/**

* @author zhuzhifei

public class ExpandableListAdapterTest extends BaseExpandableListAdapter {

public String[] groups = { "我的好友", "复旦", "南大", "同事" };

public String[][] children = { { "刘备", "曹操", "孙权", "奥巴马" },

{ "复复", "旦旦", "日月", "光华" }, { "阿南", "大大" }, { "马超", "赵云", "林丹" } };

public int[][] figures = {

{ R.drawable.lb, R.drawable.cc, R.drawable.sq, R.drawable.abm },

{ R.drawable.ff, R.drawable.dd, R.drawable.ry, R.drawable.gh },

{ R.drawable.an, R.drawable.dada },

{ R.drawable.mc, R.drawable.zy, R.drawable.ld } };

Context context;

public ExpandableListAdapterTest(Context ct) {

context = ct;

}

* 获取组数

@Override

public int getGroupCount() {

return groups.length;

}

* 获取当前组的子项

@Override

public int getChildrenCount(int groupPosition) {

return children[groupPosition].length;

}

* 获取当前组数据

@Override

public Object getGroup(int groupPosition) {

return groups[groupPosition];

}

* 获取当前子项数据

@Override

public Object getChild(int groupPosition, int childPosition) {

return children[groupPosition][childPosition];

}

* 获取组编号

@Override

public long getGroupId(int groupPosition) {

return groupPosition;

}

* 获取子项编号

@Override

public long getChildId(int groupPosition, int childPosition) {

return childPosition;

}

* 编号是否稳定

@Override

public boolean hasStableIds() {

return true;

}

* 获取组视图

@Override

public View getGroupView(int groupPosition, boolean isExpanded,

View convertView, ViewGroup parent) {

TextView textView = getGenericView();

textView.setText(getGroup(groupPosition).toString());

return textView;

}

* 获取子视图，这里采用自定义的xml页面，包含一个图片和一个文本框

@Override

public View getChildView(int groupPosition, int childPosition,

boolean isLastChild, View convertView, ViewGroup parent) {

LayoutInflater inflater = LayoutInflater.from(context);

View layout = inflater.inflate(R.layout.evchildview, null);

TextView tvName = (TextView) layout.findViewById(R.id.tvName);

tvName.setText(getChild(groupPosition,childPosition).toString());

ImageView imgHead = (ImageView) layout.findViewById(R.id.imgHead);

imgHead.setImageResource(getFigure(groupPosition,childPosition));

return layout;

}

* 子项是否可选

@Override

public boolean isChildSelectable(int groupPosition, int childPosition) {

return true;

}

/**

* 组视图，这里只显示一个简单的文本框

* @return

public TextView getGenericView() {

AbsListView.LayoutParams lp = new AbsListView.LayoutParams(

ViewGroup.LayoutParams.MATCH_PARENT, 64);

TextView textView = new TextView(context);

textView.setLayoutParams(lp);

textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);

textView.setPadding(36, 0, 0, 0);

return textView;

}

/**

* 获取肖像编号

* @param groupPosition

* @param childPosition

* @return

public int getFigure(int groupPosition, int childPosition) {

return figures[groupPosition][childPosition];

}

第四步、AndroidManifest.xml注册Activity

<activity android:name=".ExpandableListViewTest"

android:label="@string/app_name">

<intent-filter>

</intent-filter>

</activity>

第五步、运行效果

合拢效果

展开效果

点击某项效果