android.widget.AbsListView$AdapterDataSetObserver :观察员java.lang.IllegalStateException未注册

Question

我正在尝试在ListView中动态添加项。

它每5秒检查一次新条目，并将其设置为list视图。

这是我的密码：

public void T2TCheck(){
        try {
            Runnable runnable = new Runnable() {
                @Override
                public void run() {
                    List<MessageDB> messageDBList = MessageDB.find(MessageDB.class, "read = 0");
                    while (true) {
                        if (StaticMember.IS_ACTIVE) {
                            try {
                                for (int i = 0; i < messageDBList.size(); i++) {
                                    list.add(new com.example.admin.chatsdk.Message("", messageDBList.get(i).getMessage(), "", messageDBList.get(i).getSent() + ""));
                                    CustomAdapterM customAdapter = new CustomAdapterM(getApplicationContext(), android.R.layout.simple_list_item_1, list);
                                    lv.setAdapter((customAdapter));
                                }

                            } catch (Exception e) { e.printStackTrace();}
                        }
                        try {
                            Thread.sleep(5000);
                        } catch (Exception e) { e.printStackTrace();}
                    }
                }
            };
            Thread thread = new Thread(runnable);
            thread.start();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

我在这个声明中得到了一个例外：

lv.setAdapter((customAdapter));

我的例外是：

java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@21dbdb80 was not registered.

以下是完整的日志：

22/com.example.admin.chatsdk W/System.err﹕ java.lang.IllegalStateException: Observer android.widget.AbsListView$AdapterDataSetObserver@21dbdb80 was not registered.
04-05 21:32:19.657     507-1222/com.example.admin.chatsdk W/System.err﹕ at android.database.Observable.unregisterObserver(Observable.java:69)
04-05 21:32:19.657     507-1222/com.example.admin.chatsdk W/System.err﹕ at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
04-05 21:32:19.657     507-1222/com.example.admin.chatsdk W/System.err﹕ at android.widget.ListView.setAdapter(ListView.java:459)
04-05 21:32:19.657     507-1222/com.example.admin.chatsdk W/System.err﹕ at com.example.admin.chatsdk.Messages$2.run(Messages.java:152)
04-05 21:32:19.657     507-1222/com.example.admin.chatsdk W/System.err﹕ at java.lang.Thread.run(Thread.java:841)

请指导我解决这个问题。提前鸣谢。

Answer 1

正如您在我的问题中看到的那样，我在一个CustomAdapterM for loop 中创建了对象，这是错误的。

解决这一问题的步骤：

1)在onCreate方法中，我创建了adapter object并将adapter设置为listview。

CustomAdapterM customAdapter = new CustomAdapterM(getApplicationContext(), android.R.layout.simple_list_item_1, list);
lv.setAdapter((customAdapter));

2)并在向列表中添加新项后调用notifyDataSetChanged()函数：

for (int i = 0; i < messageDBList.size(); i++) {
    list.add(new com.example.admin.chatsdk.Message("", messageDBList.get(i).getMessage(), "", messageDBList.get(i).getSent() + ""));
}
customAdapter.notifyDataSetChanged();

Answer 2

下面的代码不应该在循环的外部吗？：

     CustomAdapterM customAdapter = new  CustomAdapterM(getApplicationContext(), android.R.layout.simple_list_item_1, list);
     lv.setAdapter((customAdapter));