Question

我需要在asynctask运行时向用户显示一个微调器：

public class RecoverListTask extends AsyncTask<Void, Void, Void> {
private ProgressDialog spinner;
private Context context;

public RecoverListTask(Context c) {
    context = c;
    spinner = new ProgressDialog(context); // spinner
}

@Override
protected void onPreExecute() {
    // show progress spinner
    spinner.setMessage("Downloading Podcats List");
    spinner.show();

        //do something
}

    @Override
protected void onPostExecute(Void v) {
    spinner.dismiss();
}
}

（我只粘贴了关于微调器的部分）但是当我尝试运行app时，我有这个错误：

11-05 18:02:49.077: E/WindowManager(28986): Activity com.example.podcast610downloader.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{4264ef28 V.E..... R....... 0,0-684,192} that was originally added here
11-05 18:02:49.077: E/WindowManager(28986): android.view.WindowLeaked: Activity com.example.podcast610downloader.MainActivity has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{4264ef28 V.E..... R....... 0,0-684,192} that was originally added here
11-05 18:02:49.077: E/WindowManager(28986):     at android.view.ViewRootImpl.<init>(ViewRootImpl.java:345)
11-05 18:02:49.077: E/WindowManager(28986):     at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:239)
11-05 18:02:49.077: E/WindowManager(28986):     at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.Dialog.show(Dialog.java:281)
11-05 18:02:49.077: E/WindowManager(28986):     at com.example.podcast610downloader.RecoverListTask.onPreExecute(RecoverListTask.java:31)
11-05 18:02:49.077: E/WindowManager(28986):     at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
11-05 18:02:49.077: E/WindowManager(28986):     at android.os.AsyncTask.execute(AsyncTask.java:534)
11-05 18:02:49.077: E/WindowManager(28986):     at com.example.podcast610downloader.MainActivity.onCreate(MainActivity.java:24)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.Activity.performCreate(Activity.java:5133)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
11-05 18:02:49.077: E/WindowManager(28986):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-05 18:02:49.077: E/WindowManager(28986):     at android.os.Looper.loop(Looper.java:137)
11-05 18:02:49.077: E/WindowManager(28986):     at android.app.ActivityThread.main(ActivityThread.java:5103)
11-05 18:02:49.077: E/WindowManager(28986):     at java.lang.reflect.Method.invokeNative(Native Method)
11-05 18:02:49.077: E/WindowManager(28986):     at java.lang.reflect.Method.invoke(Method.java:525)
11-05 18:02:49.077: E/WindowManager(28986):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-05 18:02:49.077: E/WindowManager(28986):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-05 18:02:49.077: E/WindowManager(28986):     at dalvik.system.NativeStart.main(Native Method)

onCreate code：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //recover list of available podcast (with details)
    RecoverListTask task = new RecoverListTask(this);
    task.execute(null, null, null);

    listView = (ListView) findViewById(R.id.listView);
    arrayAdapter=new ArrayAdapter<PodcastFile>(this, android.R.layout.simple_list_item_1);
    listView.setAdapter(arrayAdapter);
    listView.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {
            // TODO Auto-generated method stub

        }

    });

}

问题是什么？

Answer 1

不要保留对上下文变量的引用。它显然是无用的，这就是保留你的活动实例的东西。

只需删除以下行：

private Context context;
context = c;

EDIT_的 _ __ _ __ _ ___

好的，我会这样做：

public class MainActivity extends Activity { private ProgressDialog spinner; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); spinner = new ProgressDialog(this); // show progress spinner spinner.setMessage("Downloading Podcats List"); spinner.show(); // recover list of available podcast (with details) RecoverListTask task = new RecoverListTask(); task.execute(null, null, null); } private void onLoadingComplete() { spinner.dismiss(); } public class RecoverListTask extends AsyncTask<Void, Void, Void> { public RecoverListTask() {} @Override protected void onPreExecute() { } @Override protected void onPostExecute(Void v) { onLoadingComplete(); } @Override protected Void doInBackground(Void... params) { // do something //If you want to get a reference to the Activity use //MainActivity.this instead of context return null; } } }

Answer 2

我认为在实例化Asynctask时，您正在通过getApplicationContext()

传递上下文

new RecoverListTask(getApplicationContext()).execute();

相反，尝试这样做

 new RecoverListTask(MainActivity.this).execute();

检查它是否有效！

执行AsyncTask时循环进度条：错误

2 个答案: