Android:AsyncTask，在完成inInBackground之前启动onPostExecute [英] Android: AsyncTask, onPostExecute starts before doInBackground has finished

问题描述

几个小时前我遇到了这个问题(

I had this problem a few hours ago (Android: AsyncTask, my 1st task has not finished when the other starts) I put it as solved but then I realized I had a similar problem.

这是我的主要课程"GameActivity"

Here is my main class "GameActivity"

              public void mainmethod()
                    Log.w("GAMEACTIVITY","actionup");
                    myAsyncRunnable mar = new myAsyncRunnable(GameActivity.this);
                    mar.execute("fire");

public void doPhotoTask() {
    PhotoTask photoTask = new PhotoTask(camera,surfaceCamera,isPreview,holder,GameActivity.this);
    photoTask.execute(null);
}

在myAsyncRunnable.fire()中，

我有一个循环，其循环更改是gameActivity中ImageView图像的10倍以上.我希望在更改了最后一张图像后启动photoTask 在这里，myAsyncRunnable中的代码扩展了AsyncTask

in myAsyncRunnable.fire() I have a loop that changes >10 times the image of an ImageView in gameActivity. I want the photoTask to start when the last image has been changed Here the code in myAsyncRunnable extends AsyncTask

@Override
protected Void doInBackground(String... params) {
fire();
return null;
}

public void fire() {
        final ImageView image3 = (ImageView) gameactivity.findViewById(R.id.imageView3);
        final int drawables[] = new int[] {R.drawable.fire1,R.drawable.fire2,R.drawable.fire3,R.drawable.fire4,R.drawable.fire5,R.drawable.fire6,R.drawable.fire7,R.drawable.fire8,R.drawable.fire9,R.drawable.fire10,R.drawable.fire11,R.drawable.fire12,R.drawable.fire13,R.drawable.fire14,R.drawable.fire15,R.drawable.fire16};
        for (int i=0;i<drawables.length;i++) {
            final int j=i;
            Runnable runnable = new Runnable() {
                @Override
                public void run() {
                    image3.setImageResource(drawables[j]);
                     Log.w("GAMEACTIVITY","image"+j);
                }
            };
            gameactivity.handler.postDelayed(runnable, 200*j);
        }
    }

@Override
protected void  onPostExecute(Void result)  {
    Log.w("GAMEACTIVITY","ONPOSTEXECUTE");
    gameactivity.doPhotoTask();
}

在PhotoTask中

in PhotoTask

@Override
    protected Void doInBackground(Boolean... params) {
         camera.takePicture(null,null, myPictureCallback_JPG);
            Log.w("GAMEACTIVITY","TAKEPICTURE");

            return null;
    }

我的原木猫

02-11 16:03:32.920: W/GAMEACTIVITY(7750): actionup
02-11 16:03:33.010: W/GAMEACTIVITY(7750): image0
02-11 16:03:33.010: W/GAMEACTIVITY(7750): ONPOSTEXECUTE
02-11 16:03:33.030: E/QualcommCameraHardware(99): takePicture(479)
02-11 16:03:33.100: E/QualcommCameraHardware(99): rawsize = 460800 cbcr offset =307200
02-11 16:03:33.110: E/QualcommCameraHardware(99): takePicture: X
02-11 16:03:33.110: W/GAMEACTIVITY(7750): TAKEPICTURE
02-11 16:03:33.120: E/mm-camera(99): camera_ops_start, CAMERA_OPS_CAPTURE_AND_ENCODE mode 1
02-11 16:03:33.350: W/GAMEACTIVITY(7750): image1
02-11 16:03:33.490: W/GAMEACTIVITY(7750): image2
02-11 16:03:33.780: W/GAMEACTIVITY(7750): image3
02-11 16:03:33.880: W/GAMEACTIVITY(7750): image4
02-11 16:03:34.110: W/GAMEACTIVITY(7750): image5
02-11 16:03:34.250: W/GAMEACTIVITY(7750): image6
02-11 16:03:34.490: W/GAMEACTIVITY(7750): image7
02-11 16:03:34.680: W/GAMEACTIVITY(7750): image8
02-11 16:03:34.880: W/GAMEACTIVITY(7750): image9
02-11 16:03:35.050: W/GAMEACTIVITY(7750): image10
02-11 16:03:35.110: E/QualcommCameraHardware(99): receiveRawPicture: E
02-11 16:03:35.280: W/GAMEACTIVITY(7750): image11
02-11 16:03:35.440: W/GAMEACTIVITY(7750): image12
02-11 16:03:35.500: E/QualcommCameraHardware(99): address of Jpeg 0 encoded buf 1085800448 Jpeg Heap base 1085800448
02-11 16:03:35.500: W/GAMEACTIVITY(7750): FIRST
02-11 16:03:36.470: W/GAMEACTIVITY(7750): INTENT
02-11 16:03:36.580: W/GAMEACTIVITY(7750): image13
02-11 16:03:36.710: W/GAMEACTIVITY(7750): image14
02-11 16:03:36.800: W/GAMEACTIVITY(7750): image15
02-11 16:03:37.320: W/GAMEACTIVITY(7750): SURFACEDESTROYED

推荐答案

所以问题是您要安排将来的可运行对象以供将来执行，然后从doInBackground返回-这会立即激活您的onPostExecute函数.

So the problem is you are timing future runnables for future execution, and then returning from the doInBackground - which immidiatly activates your onPostExecute function.

解决您的问题的方法不是使用onPostExcute，而是为另一个Runnable加上您要在所有其他代码之后运行的代码，因为它们都在同一线程上运行，这应该可以解决您的问题.

a solution to your problem is not to use the onPostExcute but instead to time another Runnable with the code you want to run after all the others, since they all run on the same thread this should solve your problem.

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