我有 AsyncTask 扩展类我想显示进度对话框,所以我使用以下代码
class EncounterBackgroundWorker extends AsyncTask<Void, Void, Void> {
ProgressDialog connectionProgressDialog;
@Override
protected void onPreExecute() {
connectionProgressDialog = new ProgressDialog(null);
connectionProgressDialog.setCancelable(false);
connectionProgressDialog.setCanceledOnTouchOutside(false);
connectionProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
connectionProgressDialog.setMessage("Uploading Leads...");
connectionProgressDialog.show();
}
}
调用它
public class ChemoUnit extends Fragment {
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(
R.layout.chemounit,
container,
false);
//Intialize the record Grid
LinearLayout formLayout = (LinearLayout)view.findViewById(R.id.ChemoUnitGrid);
formLayout.removeAllViews();
MainGrid = new ListView(getActivity().getApplicationContext());
MainGrid.setVisibility(ListView.VISIBLE);
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.RIGHT;
MainGrid.setLayoutParams(params);
//1. set the header
ViewGroup header = (ViewGroup)inflater.inflate(R.layout.chemounitgridheader, MainGrid, false);
MainGrid.addHeaderView(header, null, false);
//2. Call the web Service
new EncounterBackgroundWorker( getActivity()).execute();
MainGrid.setAdapter(new Encounteradapter(view.getContext(), null));
// Finally add it
formLayout.addView(MainGrid);
// Return the Result
return inflater.inflate(R.layout.chemounit, container, false);
}
}
但它总是崩溃,我不知道如何初始化进度并将上下文添加到 i1t,给这个日志
06-10 14:49:48.665: D/dalvikvm(10728): GC_CONCURRENT freed 143K, 4% free 6768K/6983K, paused 3ms+4ms
06-10 14:49:51.465: D/dalvikvm(10728): GC_FOR_ALLOC freed 46K, 4% free 6824K/7047K, paused 39ms
06-10 14:49:51.465: I/dalvikvm-heap(10728): Grow heap (frag case) to 7.223MB for 513744-byte allocation
06-10 14:49:51.505: D/dalvikvm(10728): GC_FOR_ALLOC freed <1K, 4% free 7326K/7559K, paused 25ms
06-10 14:49:51.535: I/System.out(10728): Chemo Unit
06-10 14:49:51.540: I/System.out(10728): Next Appointement
06-10 14:49:51.545: I/System.out(10728): Change Booking
06-10 14:49:51.545: I/System.out(10728): Booking
06-10 14:49:51.550: D/dalvikvm(10728): GC_CONCURRENT freed 3K, 3% free 7353K/7559K, paused 2ms+4ms
06-10 14:49:51.555: I/System.out(10728): Chemo Unit
06-10 14:49:51.555: I/System.out(10728): Next Appointement
06-10 14:49:51.560: I/System.out(10728): Change Booking
06-10 14:49:51.565: I/System.out(10728): Booking
06-10 14:49:51.565: I/System.out(10728): Chemo Unit
06-10 14:49:51.570: I/System.out(10728): Next Appointement
06-10 14:49:51.570: I/System.out(10728): Change Booking
06-10 14:49:51.570: I/System.out(10728): Booking
06-10 14:49:51.575: I/System.out(10728): Chemo Unit
06-10 14:49:51.575: I/System.out(10728): Next Appointement
06-10 14:49:51.585: I/System.out(10728): Change Booking
06-10 14:49:51.590: I/System.out(10728): Booking
06-10 14:49:51.590: I/System.out(10728): Chemo Unit
06-10 14:49:51.595: I/System.out(10728): Next Appointement
06-10 14:49:51.595: I/System.out(10728): Change Booking
06-10 14:49:51.600: I/System.out(10728): Booking
06-10 14:49:55.410: D/CLIPBOARD(10728): Hide Clipboard dialog at Starting input: finished by someone else... !
06-10 14:50:00.075: I/System.out(10728): Chemo Unit
06-10 14:50:00.080: I/System.out(10728): Next Appointement
06-10 14:50:00.085: I/System.out(10728): Change Booking
06-10 14:50:00.090: I/System.out(10728): Booking
06-10 14:50:00.090: I/System.out(10728): Chemo Unit
06-10 14:50:00.090: I/System.out(10728): Next Appointement
06-10 14:50:00.095: I/System.out(10728): Change Booking
06-10 14:50:00.095: I/System.out(10728): Booking
06-10 14:50:00.100: I/System.out(10728): Chemo Unit
06-10 14:50:00.100: I/System.out(10728): Next Appointement
06-10 14:50:00.105: I/System.out(10728): Change Booking
06-10 14:50:00.105: I/System.out(10728): Booking
06-10 14:50:00.105: I/System.out(10728): Chemo Unit
06-10 14:50:00.105: I/System.out(10728): Next Appointement
06-10 14:50:00.105: I/System.out(10728): Change Booking
06-10 14:50:00.110: I/System.out(10728): Booking
06-10 14:50:01.995: I/System.out(10728): Chemo Unit
06-10 14:50:01.995: I/System.out(10728): Next Appointement
06-10 14:50:01.995: I/System.out(10728): Change Booking
06-10 14:50:02.005: I/System.out(10728): Booking
06-10 14:50:02.010: I/System.out(10728): Chemo Unit
06-10 14:50:02.010: I/System.out(10728): Next Appointement
06-10 14:50:02.010: I/System.out(10728): Change Booking
06-10 14:50:02.010: I/System.out(10728): Booking
06-10 14:50:02.015: I/System.out(10728): Chemo Unit
06-10 14:50:02.015: I/System.out(10728): Next Appointement
06-10 14:50:02.015: I/System.out(10728): Change Booking
06-10 14:50:02.015: I/System.out(10728): Booking
06-10 14:50:02.020: I/System.out(10728): Chemo Unit
06-10 14:50:02.020: I/System.out(10728): Next Appointement
06-10 14:50:02.020: I/System.out(10728): Change Booking
06-10 14:50:02.020: I/System.out(10728): Booking
06-10 14:50:02.050: D/AndroidRuntime(10728): Shutting down VM
06-10 14:50:02.050: W/dalvikvm(10728): threadid=1: thread exiting with uncaught exception (group=0x401b4760)
06-10 14:50:02.050: E/AndroidRuntime(10728): FATAL EXCEPTION: main
06-10 14:50:02.050: E/AndroidRuntime(10728): java.lang.NullPointerException
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.app.AlertDialog.resolveDialogTheme(AlertDialog.java:120)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.app.AlertDialog.<init>(AlertDialog.java:80)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.app.ProgressDialog.<init>(ProgressDialog.java:76)
06-10 14:50:02.050: E/AndroidRuntime(10728): at com.appnetics.EncounterBackgroundWorker.onPreExecute(EncounterBackgroundWorker.java:45)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:549)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.os.AsyncTask.execute(AsyncTask.java:499)
06-10 14:50:02.050: E/AndroidRuntime(10728): at com.appnetics.ChemoUnit.onCreateView(ChemoUnit.java:63)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:870)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:622)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:420)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.os.Handler.handleCallback(Handler.java:587)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.os.Handler.dispatchMessage(Handler.java:92)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.os.Looper.loop(Looper.java:132)
06-10 14:50:02.050: E/AndroidRuntime(10728): at android.app.ActivityThread.main(ActivityThread.java:4123)
06-10 14:50:02.050: E/AndroidRuntime(10728): at java.lang.reflect.Method.invokeNative(Native Method)
06-10 14:50:02.050: E/AndroidRuntime(10728): at java.lang.reflect.Method.invoke(Method.java:491)
06-10 14:50:02.050: E/AndroidRuntime(10728): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)
06-10 14:50:02.050: E/AndroidRuntime(10728): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)
06-10 14:50:02.050: E/AndroidRuntime(10728): at dalvik.system.NativeStart.main(Native Method)