Question

我正在编写一个程序，从服务器（使用JSON）从MySql获取数据，并相应地更新UI ，

我从服务器

使用 AsyncTask 获取两种类型的数据

1) Bubble Answers
2) Comments

parseBubbleAnswers方法成功运行并更新UI，但parseComments类是AsyncTask，在doInBackground中调用parseComments方法，没有运行runOnUiThread(new Runnable() { run() });

任何人都可以帮我解决这个问题

这是我的代码：

public class FetchServer extends Activity
{
    protected void onCreate(Bundle savedInstanceState) 
    {
        String photoId = "1"; // photo id for which the data is fetched
        checkBubbleData(photoId); // which call AsyncTask - 2 differnt calls
    }
    public void checkBubbleData(String photoId)
    {
        new parseBubbleAnswers().execute(photoId); // to fetch bubble answers
        new parseComments().execute(photoId); // to fetch comments
    }
    class parseBubbleAnswers extends AsyncTask<String, Integer,String> 
    {

        @Override
        protected String doInBackground(String... params) 
        {
            // TODO Auto-generated method stub
            Looper.prepare();
            parseBubbleAnswers(); // which has runOnUiThread(new Runnable() which updates (successfully !) the UI
            return null;
        }
    }
    class parseComments extends AsyncTask<String, Integer,String> 
    {

        @Override
        protected String doInBackground(String... params) 
        {
            // TODO Auto-generated method stub
            Looper.prepare();

            String parseComReturn = parseComments();
            if(parseComReturn=="end")
            {
                commentBuilder(); // which will update UI after fetch data by parseComments() method
            }
        }
    }
    public void commentBuilder()
    {
        runOnUiThread(new Runnable() // while debugging, it comes here, on Step Over it stick for 2 times and then move at the end of method without error 
        {       
            public void run() 
            {
                // update UI code
            }
        });
    }
}

Answer 1

尝试这种方式：

首先创建一个Handler：

Handler mHandler = new Handler();

更改此内容，

public void commentBuilder()
    {
        runOnUiThread(new Runnable() // while debugging, it comes here, on Step Over it stick for 2 times and then move at the end of method without error 
        {       
            public void run() 
            {
                // update UI code
            }
        });
    }

。通过，

public void commentBuilder() { new Thread(new Runnable() { @Override public void run() { // TODO Auto-generated method stub while (isRunning) { try { // Thread.sleep(10000); mHandler.post(new Runnable() { @Override public void run() { // TODO Auto-generated method stub // Write your code here to update the UI. } }); } catch (Exception e) { // TODO: handle exception } } } }).start(); }

完成UI后停止线程，

isRunning = false;

编辑：

尝试以这种方式使用异步任务：

class parseComments extends AsyncTask<String, Integer,String> { protected String doInBackground(String... params) { String parseComReturn = parseComments(); return parseComReturn; } protected void onPostExecute(String result) { if(result.equals("end")) { commentBuilder(); } } }

感谢。

Answer 2

runOnUiThread是Activity的方法，AsyncTask没有引用活动。

然而，AsyncTask已经在UI线程上运行，并且正是为此而设计的。

只需处理onPostExecute中的用户界面更改。

Answer 3

我遇到了类似的问题。

只需将Activity类的引用传递给parseComments类。

class parseComments extends AsyncTask<String, Integer,String>{

 Activity activity;
 public parseComments(Activity activity){
  this.activity = activity;
 }
}

之后，您可以将runOnUiThread用作

activity.runOnUiThread(new Runnable(){
  @Override
  public void run(){

  }
});

仅适用于Activity类。不是上下文类。

runOnUiThread未在AsyncTask中运行

3 个答案: