线程无效。应用程序关闭未完成。

Question

我正在尝试在按下刷新按钮时在我的程序中显示进度对话框，但是应用程序在调试器中关闭了一个错误，但是创建的线程ui hierachy只能触摸它。

    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

您正在从非ui线程调用ui操作，您可以使用runOnUiThread ..
或者更好地使用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();
}
}

Answer 2

您无法使用UI来自Thread进行操纵！它是被禁止！如果您想更新UI，请使用

• 的 runOnUiThread()
• 的 AsyncTask

所以试试这样：

runOnUiThread(new Runnable() {

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

   }
});

AsyncTask更复杂，也是泛型类型，提供类型控制等一些好处。您可以在此处查看示例：

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