QRScanner/mobile/src/main/java/cz/cvut/fel/dce/qrscanner/mupdf/CancellableAsyncTask.java

   1 package cz.cvut.fel.dce.qrscanner.mupdf;
   2
   3 import java.util.concurrent.CancellationException;
   4 import java.util.concurrent.ExecutionException;
   5
   6 // Ideally this would be a subclass of AsyncTask, however the cancel() method is final, and cannot
   7 // be overridden. I felt that having two different, but similar cancel methods was a bad idea.
   8 public class CancellableAsyncTask<Params, Result>
   9 {
  10         private final AsyncTask<Params, Void, Result> asyncTask;
  11         private final CancellableTaskDefinition<Params, Result> ourTask;
  12
  13         public void onPreExecute()
  14         {
  15
  16         }
  17
  18         public void onPostExecute(Result result)
  19         {
  20
  21         }
  22
  23         public CancellableAsyncTask(final CancellableTaskDefinition<Params, Result> task)
  24         {
  25                 if (task == null)
  26                                 throw new IllegalArgumentException();
  27
  28                 this.ourTask = task;
  29                 asyncTask = new AsyncTask<Params, Void, Result>()
  30                                 {
  31                                         @Override
  32                                         protected Result doInBackground(Params... params)
  33                                         {
  34                                                 return task.doInBackground(params);
  35                                         }
  36
  37                                         @Override
  38                                         protected void onPreExecute()
  39                                         {
  40                                                 CancellableAsyncTask.this.onPreExecute();
  41                                         }
  42
  43                                         @Override
  44                                         protected void onPostExecute(Result result)
  45                                         {
  46                                                 CancellableAsyncTask.this.onPostExecute(result);
  47                                                 task.doCleanup();
  48                                         }
  49                                 };
  50         }
  51
  52         public void cancelAndWait()
  53         {
  54                 this.asyncTask.cancel(true);
  55                 ourTask.doCancel();
  56
  57                 try
  58                 {
  59                         this.asyncTask.get();
  60                 }
  61                 catch (InterruptedException e)
  62                 {
  63                 }
  64                 catch (ExecutionException e)
  65                 {
  66                 }
  67                 catch (CancellationException e)
  68                 {
  69                 }
  70
  71                 ourTask.doCleanup();
  72         }
  73
  74         public void execute(Params ... params)
  75         {
  76                 asyncTask.execute(params);
  77         }
  78
  79 }