超详细实用ExpandableListView教程（有图有真相）
看到很多关于ExpandableListView的教程都是用一些简单的String[]字符串数组数据来填充列表项，这在实际项目运用中并不是很实用，下面容笔者来介绍一下如何高效有序地实用自定义实体类线性表ArrayList<Object>来填充ExpandableListView的列表项。首先我们可以定义列表项的数据实体类ContactEntry.java如下：
package com.clicknect.ichat.entry;
import android.graphics.Bitmap;
public class ContactEntry {
private String jid;
private String nickname;
private byte[] avatarByte;
private Bitmap avatarBitmap;
private boolean isOnline;
private String onlineViaResource;
public ContactEntry() {
this.jid = null;
this.nickname = null;
this.avatarByte = null;
this.avatarBitmap = null;
this.isOnline = false;
}
public String getJid() {
return jid;
}
public void setJid(String jid) {
this.jid = jid;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
public byte[] getAvatarByte() {
return avatarByte;
}
public void setAvatarByte(byte[] avatarByte) {
this.avatarByte = avatarByte;
}
public Bitmap getAvatarBitmap() {
return avatarBitmap;
}
public void setAvatarBitmap(Bitmap avatarBitmap) {
this.avatarBitmap = avatarBitmap;
}
public boolean isOnline() {
return isOnline;
}
public void setOnline(boolean isOnline) {
this.isOnline = isOnline;
}
public String getOnlineViaResource() {
return onlineViaResource;
}
public void setOnlineViaResource(String onlineViaResource) {
this.onlineViaResource = onlineViaResource;
}
}
然后我们来自定义一个ContactEntry.java类的二维数组类，解释一下这个所谓的“自定义类的二维数组类”，由于填充ExpandableListView的数据是分组的，我们把不同的组作为“自定义类的二维数组类”的第一维，然后把组中的成员（也就是ContactEntry类）作为第二维。这个“自定义类的二维数组类”ContactEntryGroupArray.java如下：
package com.clicknect.ichat.helper;
import java.util.ArrayList;
import com.clicknect.ichat.entry.ContactEntry;
/**
* 联系人对象组数组类
* 形如：ArrayList<int><ContactEntry>
* @author LiuJQ
*
*/
public class ContactEntryGroupArray {
private int[] numberOfEachGroup;
private String[] groupName;
private ArrayList<ContactEntry> contactEntryList;
public ContactEntryGroupArray(String[] groupName, int[] numberOfEachGroup, ArrayList<ContactEntry> contactEntryList){
this.groupName = groupName;
this.numberOfEachGroup = numberOfEachGroup;
this.contactEntryList = contactEntryList;
}
public String getGroupName(int groupID){
return groupID < groupName.length ? groupName[groupID] : null;
}
public ArrayList<ContactEntry> getGroup(int groupID){
if(!(groupID<groupName.length)){
return null;
}else{
ArrayList<ContactEntry> contactGroup = new ArrayList<ContactEntry>();
int start = 0;
for(int i=0;i<groupID;i++){
start += numberOfEachGroup[i];
}
int end = start + numberOfEachGroup[groupID];
copy(contactGroup,contactEntryList,start,end);
return contactGroup;
}
}
private void copy(ArrayList<ContactEntry> des, ArrayList<ContactEntry> res, int start, int end){
for(int i=start;i<end;i++){
des.add(res.get(i));
}
}
public ContactEntry getContact(int groupID, int groupPosition){
ContactEntry selectedContact = getGroup(groupID).get(groupPosition);
return selectedContact != null ? selectedContact : null;
}
public int getGroupCount(){
return groupName.length;
}
}
最后，我们来继承BaseExpandableListAdapter适配器类实现我们自己的适配器ContactGroupAdapter，有了这个适配器我们就可以很好的填充ExpandableListView组件了。适配器类ContactGroupAdapter实现如下：
package com.clicknect.ichat.adapter;
import java.util.ArrayList;
import com.clicknect.android.ichat.R;
import com.clicknect.ichat.ChatActivity;
import com.clicknect.ichat.MainActivity;
import com.clicknect.ichat.entry.ContactEntry;
import com.clicknect.ichat.helper.ContactEntryGroupArray;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;
public class ContactGroupAdapter extends BaseExpandableListAdapter {
private ContactEntryGroupArray mContactEntryGroupArray;
private Context mContext;
private LayoutInflater mLayoutInflater;
public ContactGroupAdapter(Context context, ContactEntryGroupArray contactEntryGroupArray){
mContactEntryGroupArray = contactEntryGroupArray;
mContext = context;
mLayoutInflater = LayoutInflater.from(mContext);
}
public void setData(ContactEntryGroupArray contactEntryGroupArray){
mContactEntryGroupArray = contactEntryGroupArray;
}
@Override
public Object getChild(int groupID , int groupPosition ) {
// TODO Auto-generated method stub
return mContactEntryGroupArray.getContact(groupID, groupPosition);
}
@Override
public long getChildId(int groupID, int groupPosition) {
// TODO Auto-generated method stub
return groupPosition;
}
@Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
if(convertView==null){
convertView = mLayoutInflater.inflate(R.layout.contact_listview_child_item, null);
}
final ContactEntry currentContact = mContactEntryGroupArray.getContact(groupPosition, childPosition);
TextView contactName = (TextView)convertView.findViewById(R.id.contact_listview_child_nick);
contactName.setText(currentContact.getNickname());
TextView contactStatus = (TextView)convertView.findViewById(R.id.contact_listview_child_status);
if(currentContact.isOnline()){
contactName.setTextColor(Color.GREEN);
contactStatus.setText("online");
}else{
contactName.setTextColor(Color.BLACK);
contactStatus.setText("offline");
}
return convertView;
}
@Override
public int getChildrenCount(int groupID) {
// TODO Auto-generated method stub
return mContactEntryGroupArray.getGroup(groupID).size();
}
@Override
public ArrayList<ContactEntry> getGroup(int groupID) {
// TODO Auto-generated method stub
return mContactEntryGroupArray.getGroup(groupID);
}
@Override
public int getGroupCount() {
// TODO Auto-generated method stub
return mContactEntryGroupArray.getGroupCount();
}
@Override
public long getGroupId(int groupID) {
// TODO Auto-generated method stub
return groupID;
}
@Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
if(convertView==null){
convertView = mLayoutInflater.inflate(R.layout.contact_listview_group_item, null);
}
TextView groupName = (TextView)convertView.findViewById(R.id.contact_listview_group_name);
groupName.setText(mContactEntryGroupArray.getGroupName(groupPosition));
TextView onlineNumber = (TextView)convertView.findViewById(R.id.contact_listview_group_num);
StringBuffer sb = new StringBuffer();
sb.append(getOnlineNumber(groupPosition));
sb.append('/');
sb.append(getChildrenCount(groupPosition));
onlineNumber.setText(sb.toString());
return convertView;
}
private int getOnlineNumber(int groupID){
int numberOfOnlineEntry = 0;
for(ContactEntry contactEntry : getGroup(groupID)){
if(contactEntry.isOnline()){
numberOfOnlineEntry++;
}
}
return numberOfOnlineEntry;
}
@Override
public boolean hasStableIds() {
// TODO Auto-generated method stub
return false;
}
@Override
public boolean isChildSelectable(int groupPosition, int childPosition) {
// TODO Auto-generated method stub
return true;
}
}
好了，一切准备就绪，现在我们要做的就是从布局文件中获取到ExpandableListView组件，然后利用上面适配器类的构造方法设置好数据，接下来系统便会为我们做好图形界面的渲染了：
public ContactGroupAdapter(Context context, ContactEntryGroupArray contactEntryGroupArray){
mContactEntryGroupArray = contactEntryGroupArray;
mContext = context;
mLayoutInflater = LayoutInflater.from(mContext);
}
小弟不才，各路大神别喷，菜鸟们若有问题，欢迎跟帖发问，有空我会及时回答，谢谢查看本贴。