android-如何检查后台线程是否成功？

Question

I'm trying to extract RAR files with junRAR. But as I read from this question: OutOfMemoryError when I decompress RAR file on Android , junRAR is not optimized yet for Android. So, what I want to do is to check if the extraction is successful or not, then give an error message if it fails.(because my app crashes if it the extraction is not successful). Can somebody tell me how can I do that checking? My thread is being done here:

public class MyTask extends AsyncTask<Void, Void, Void> {

  private ProgressDialog progress;
  public MyTask(ProgressDialog progress) {
      this.progress = progress;   
  }

  public void onPreExecute() {
    progress.show();
  }    
@Override
protected Void doInBackground(Void... params) {
    if(taskType==1){
         extractArchive(rarFile, destinationFolder);            
    }
return null;
}

public void onPostExecute(Void unused) {
    progress.dismiss();
    if(taskType==1){
        refreshFileList();
        Toast.makeText(MainActivity.this, "Extracted to " + targetPath, Toast.LENGTH_LONG).show();
    }
} 

Here's my Logcat error:

03-02 16:59:40.777: E/AndroidRuntime(28573): FATAL EXCEPTION: AsyncTask #1
03-02 16:59:40.777: E/AndroidRuntime(28573): java.lang.RuntimeException: An error occured while executing doInBackground()
03-02 16:59:40.777: E/AndroidRuntime(28573):    at android.os.AsyncTask$3.done(AsyncTask.java:278)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.lang.Thread.run(Thread.java:856)
03-02 16:59:40.777: E/AndroidRuntime(28573): Caused by: java.lang.OutOfMemoryError
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.unpack.ppm.SubAllocator.startSubAllocator(SubAllocator.java:146)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.unpack.ppm.ModelPPM.decodeInit(ModelPPM.java:216)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.unpack.Unpack.readTables(Unpack.java:656)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.unpack.Unpack.unpack29(Unpack.java:165)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.unpack.Unpack.doUnpack(Unpack.java:120)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.Archive.doExtractFile(Archive.java:501)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.github.junrar.Archive.extractFile(Archive.java:443)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.jearom.thesisfmanager.MainActivity.extractArchive(MainActivity.java:2270)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.jearom.thesisfmanager.MainActivity$MyTask.doInBackground(MainActivity.java:1962)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at com.jearom.thesisfmanager.MainActivity$MyTask.doInBackground(MainActivity.java:1)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
03-02 16:59:40.777: E/AndroidRuntime(28573):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
03-02 16:59:40.777: E/AndroidRuntime(28573):    ... 5 more
03-02 16:59:41.437: E/WindowManager(28573): Activity com.jearom.thesisfmanager.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@41d3a0c0 that was originally added here
03-02 16:59:41.437: E/WindowManager(28573): android.view.WindowLeaked: Activity com.jearom.thesisfmanager.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView@41d3a0c0 that was originally added here
03-02 16:59:41.437: E/WindowManager(28573):     at android.view.ViewRootImpl.(ViewRootImpl.java:344)
03-02 16:59:41.437: E/WindowManager(28573):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:267)
03-02 16:59:41.437: E/WindowManager(28573):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:215)
03-02 16:59:41.437: E/WindowManager(28573):     at android.view.WindowManagerImpl$CompatModeWrapper.addView(WindowManagerImpl.java:140)
03-02 16:59:41.437: E/WindowManager(28573):     at android.view.Window$LocalWindowManager.addView(Window.java:537)
03-02 16:59:41.437: E/WindowManager(28573):     at android.app.Dialog.show(Dialog.java:278)
03-02 16:59:41.437: E/WindowManager(28573):     at com.jearom.thesisfmanager.MainActivity$MyTask.onPreExecute(MainActivity.java:1867)
03-02 16:59:41.437: E/WindowManager(28573):     at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:561)
03-02 16:59:41.437: E/WindowManager(28573):     at android.os.AsyncTask.execute(AsyncTask.java:511)
03-02 16:59:41.437: E/WindowManager(28573):     at com.jearom.thesisfmanager.MainActivity$6.onClick(MainActivity.java:752)
03-02 16:59:41.437: E/WindowManager(28573):     at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
03-02 16:59:41.437: E/WindowManager(28573):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-02 16:59:41.437: E/WindowManager(28573):     at android.os.Looper.loop(Looper.java:137)
03-02 16:59:41.437: E/WindowManager(28573):     at android.app.ActivityThread.main(ActivityThread.java:4456)
03-02 16:59:41.437: E/WindowManager(28573):     at java.lang.reflect.Method.invokeNative(Native Method)
03-02 16:59:41.437: E/WindowManager(28573):     at java.lang.reflect.Method.invoke(Method.java:511)
03-02 16:59:41.437: E/WindowManager(28573):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
03-02 16:59:41.437: E/WindowManager(28573):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
03-02 16:59:41.437: E/WindowManager(28573):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

onPostExecute(Result) invoked on the UI thread after the background computation finishes. The result of the background computation is passed to this method as a parameter.

For more information : http://developer.android.com/reference/android/os/AsyncTask.html

Here is one example

  private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
  protected Long doInBackground(URL... urls) {
     int count = urls.length;
     long totalSize = 0;
     for (int i = 0; i < count; i++) {
         totalSize += Downloader.downloadFile(urls[i]);
         publishProgress((int) ((i / (float) count) * 100));
         // Escape early if cancel() is called
         if (isCancelled()) break;
     }
     return totalSize;
  }

  protected void onProgressUpdate(Integer... progress) {
     setProgressPercent(progress[0]);
  }

  protected void onPostExecute(Long result) {
     showDialog("Downloaded " + result + " bytes");
  }
}

Answer 2

You can solve this problem using SharedPreferences by creating a SharedPreference file that hold the state of each action you perform on a file using it name as a KEY and a boolean value that describe the state of it either succeeded in extraction or not. Also make your method return true if the process succeded and false otherwise.

Modify your constructor as the following to save the context of the app

private ProgressDialog progress;
private Context mContext;
public MyTask(ProgressDialog progress, Context context) {
  this.progress = progress;   
  this.mContext = context;
}

Replace your doInBackground method with this one:

@Override
protected Void doInBackground(Void... params) {
if(taskType==1){
     if(extractArchive(rarFile, destinationFolder)){
        SharedPreferences myLog = mContext.getSharedPreferences("state_holder", Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = myLog.edit();
        editor.putBoolean("file_name", true);
        editor.commit();
   }            
}
return null;
}    

More info about SharedPReference in this LINK