android中ListView数据刷新时的同步方法

本文实例讲述了android中listview数据刷新时的同步方法。分享给大家供大家参考。具体实现方法如下：

public class main extends baseactivity { 
 private static final string tag = "tag"; 
 private static final int status_change = 0; 
 expandablelistview melv; 
 arraylist<groupinfo> mgrouparray; 
 @override 
 public void oncreate(bundle savedinstancestate) { 
  super.oncreate(savedinstancestate); 
  setcontentview(r.layout.main); 
  melv = (expandablelistview) findviewbyid(r.id.contact_list); 
  mstatus = (textview) findviewbyid(r.id.setstatus); 
  mgrouparray = getintent().getparcelablearraylistextra("grouparray");// => 取数据 
  mexpandableadapter = new expandableadapter(this, main.this); 
  melv.setadapter(mexpandableadapter);   
  // 异步对比服务器分组和本地分组 
  handlerthread handlerthread = new handlerthread("handler_thread"); 
  handlerthread.start(); 
  updategrouphandler myhandler = new updategrouphandler( 
    handlerthread.getlooper()); 
  message message = myhandler.obtainmessage(); 
  message.sendtotarget(); 
  mhandler = new handler() { 
   public void handlemessage(message msg) { 
    switch (msg.what) { 
    case status_change: 
     // 处理ui更新等操作 
     updateui(); 
     break; 
    } 
   }; 
  };  
 } 
 /** 
  * 发送消息更新ui 
  */ 
 private void sendmessagetoupdateui() { 
  message msg = new message(); 
  msg.what = status_change; 
  mhandler.sendmessage(msg);
  // 向handler发送消息,更新ui 
 } 
 private void updateui() { 
  // 详细的更新 
  mexpandableadapter.notifydatasetchanged();
  // 更新expandablelistview 
 } 
 /** 
  * 异步刷新分组的handler 
  * 
  * @author administrator 
  * 
  */ 
 class updategrouphandler extends handler { 
  public updategrouphandler() { 
  } 
  public updategrouphandler(looper looper) { 
   super(looper); 
  } 
  @override 
  public void handlemessage(message msg) { 
   contactsmanagerdbadapter dbadapter = new contactsmanagerdbadapter( 
     main.this); 
   dbadapter.open(); 
   // =>dosomething... 
   mgrouparray = grouplist; 
   system.out.println("========数据更新后,刷新listview========="); 
   sendmessagetoupdateui(); 
  } 
 } 
 private class expandableadapter extends baseexpandablelistadapter { 
  activity activity; 
  layoutinflater layoutinflater; 
  public expandableadapter(activity a, context context) { 
   activity = a; 
   layoutinflater = (layoutinflater) context 
     .getsystemservice(context.layout_inflater_service); 
  } 
  public object getchild(int groupposition, int childposition) { 
   return mgrouparray.get(groupposition).getchildlist() 
     .get(childposition); 
  } 
  public long getchildid(int groupposition, int childposition) { 
   return childposition; 
  } 
  public int getchildrencount(int groupposition) { 
   return mgrouparray.get(groupposition).getchildlist().size(); 
  } 
  public view getchildview(int groupposition, int childposition, 
    boolean islastchild, view convertview, viewgroup parent) { 
   // ..... 
   return vi; 
  } 
  public object getgroup(int groupposition) { 
   return mgrouparray.get(groupposition); 
  } 
  public int getgroupcount() { 
   return mgrouparray.size(); 
  } 
  public long getgroupid(int groupposition) { 
   return groupposition; 
  } 
  public view getgroupview(int groupposition, boolean isexpanded, 
    view convertview, viewgroup parent) { 
   groupinfo groupinfo = mgrouparray.get(groupposition); 
   string string = groupinfo.getname(); 
   convertview = (view) layoutinflater.inflate(r.layout.group_layout, 
     null); 
   final textview textview = (textview) convertview 
     .findviewbyid(r.id.groupname); 
   if (textview != null) { 
    textview.settext(string); 
   } 
   return convertview; 
  } 
  public boolean hasstableids() { 
   return true; 
  } 
  public boolean ischildselectable(int groupposition, int childposition) { 
   return true; 
  } 
 } 
}

代码只是提取的部分,应该没多大影响.

上面集合mgrouparray存在数据共享,测试多次发现报错有两种:

=>1.java.lang.indexoutofboundsexception: invalid location 3, size is 3
=>2.the content of the adapter has changed but listview did not receive a notification. make sure the content of your adapter is not modified from a background thread, but only from the ui thread.

第一个问题,数据同步问题,我弄了下没解决.
第二个问题,改变适配器adapter内容时不要在后台线程中,必须在ui线程中处理
我将上面子线程updategrouphandler里的数据更新利用handler提取到了主线程赋值

message.obj = grouplist;

额,改好后测试多次,发现这两问题都解决了,发现还是对handler理解的不够.

发下更改的代码段:

@override 
public void oncreate(bundle savedinstancestate) { 
 super.oncreate(savedinstancestate); 
 setcontentview(r.layout.main); 
 melv = (expandablelistview) findviewbyid(r.id.contact_list); 
 mstatus = (textview) findviewbyid(r.id.setstatus); 
 mgrouparray = getintent().getparcelablearraylistextra("grouparray");
 // => 取数据 
 mexpandableadapter = new expandableadapter(this, main.this); 
 melv.setadapter(mexpandableadapter);   
 // 异步对比服务器分组和本地分组 
 handlerthread handlerthread = new handlerthread("handler_thread"); 
 handlerthread.start(); 
 updategrouphandler myhandler = new updategrouphandler( 
   handlerthread.getlooper()); 
 message message = myhandler.obtainmessage(); 
 message.sendtotarget(); 
 mhandler = new handler() { 
  public void handlemessage(message msg) { 
   switch (msg.what) { 
   case status_change: 
    // 处理ui更新等操作 
    updateui(msg.obj); 
    break; 
   } 
  }; 
 };  
} 
/** 
* 发送消息更新ui 
*/ 
private void sendmessagetoupdateui(arraylist<groupinfo> grouplist) { 
 message msg = new message(); 
 msg.what = status_change; 
 msg.obj = grouplist; 
 mhandler.sendmessage(msg);
 // 向handler发送消息,更新ui 
} 
 @suppresswarnings("unchecked") 
private void updateui(object obj) { 
 // 详细的更新 
 mgrouparray = (arraylist<groupinfo>) obj; 
 mexpandableadapter.notifydatasetchanged();
 // 更新expandablelistview 
} 
/** 
 * 异步刷新分组的handler 
 * 
 * @author administrator 
 * 
 */ 
class updategrouphandler extends handler { 
 public updategrouphandler() { 
 } 
 public updategrouphandler(looper looper) { 
  super(looper); 
 } 
 @override 
 public void handlemessage(message msg) { 
  contactsmanagerdbadapter dbadapter = new contactsmanagerdbadapter( 
    main.this); 
  dbadapter.open(); 
  // =>dosomething... 
  system.out.println("========数据更新后,刷新listview========="); 
  sendmessagetoupdateui(grouplist); 
 } 
}

希望本文所述对大家的android程序设计有所帮助。