線程無法工作。應用程序關閉未解決。

Question

我試圖在程序中顯示進度對話框，當按下刷新按鈕但應用程序關閉未解決的錯誤在調試器中創建的線程層次只能觸摸它。

public class MainActivity extends Activity { 
    Handler handler = new Handler(); 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     this.refreshView(); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.activity_main, menu); 
     return true; 
    } 

    public void refreshView(){ 
     ImageView img = (ImageView) findViewById(R.id.imageView1); 
     Bitmap bm = null; 
     InputStream is = null; 
     BufferedInputStream bis = null; 
     try 
     { 
      URLConnection conn = new URL("http://technomoot.edu.pk/$Common/Image/Content/ciit_logo.jpg").openConnection(); 
      conn.connect(); 
      is = conn.getInputStream(); 
      bis = new BufferedInputStream(is, 8192); 
      bm = BitmapFactory.decodeStream(bis); 
     } 
     catch (Exception e) 
     { 
      e.printStackTrace(); 
     } 
     finally { 
      if (bis != null) 
      { 
       try 
       { 
        bis.close(); 
       } 
       catch (IOException e) 
       { 
        e.printStackTrace(); 
       } 
      } 
      if (is != null) 
      { 
       try 
       { 
        is.close(); 
       } 
       catch (IOException e) 
       { 
        e.printStackTrace(); 
       } 
      } 
     } 
     img.setImageBitmap(bm); 
} 

    public void onRefresh(View view) { 

     final ProgressDialog dialog = ProgressDialog.show(this,"Loading","Loading the image of the Day"); 
     Thread th = new Thread(){ 
      public void run(){ 
       refreshView(); 
       handler.post(new Runnable(){ 
        public void run(){ 
         dialog.dismiss(); 
        } 
       } 
         ); 
      } 

     };th.start(); 
    } 

} 

Answer 1

你不能UI從工人Thread操縱！它是被禁止！如果您想更新UI只使用

• runOnUiThread()
• AsyncTask

因此，嘗試這樣的：

runOnUiThread(new Runnable() { 

    @Override 
    public void run() { 
     // do your work. 

    } 
}); 

AsyncTask比較複雜，也類屬提供som的類型喜歡類型的控制等。e好處你可以看一下這裏的例子：

• Android application (performance and more) analysis tools - Tutorial

Answer 2

要調用從一個非UI線程的UI操作，您可以使用runOnUiThread ..
或更好地利用AsynchTask

public YourTask extends AsyncTask<Object,Object,Object>{ //change Object to required type 
    ProgressDialog dialog; 
    Context context; 

public YourTask(Context context){ 
    this.context=context; 
} 

protected void onPreExecute(Object o){ 
    dialog = ProgressDialog.show(this,"Loading","Loading the image of the Day"); 
} 

protected void doInBackground(Object o){ 
    refreshView(); 
} 

protected void onPostExecute(Object o){ 
    img.setImageBitmap(bm); 
    dialog.dismiss(); 
} 
}