ParseObject.pinAllInBackground() results with NullPointerException

问题

I have a News objects that extends ParseObject class. I'd like it to be cached locally so that I can fetch it from local store later.

Here is my callback that includes call to .pinAllInBackground(..) method:

    FindCallback<News> onNewsReceived = new FindCallback<News>() {

    @Override
    public void done(List<News> arg0, ParseException arg1) {

        if (arg1 == null) {

            newsList = new ArrayList<News>(arg0);
            ParseObject.pinAllInBackground(newsList);
            initializeList();


        } else {
            Log.d("TAG1", String.valueOf(arg1.getMessage()));
        }

    }
};

When i run this I get the following exception:

    09-22 11:31:25.637: E/AndroidRuntime(27380): FATAL EXCEPTION: main
09-22 11:31:25.637: E/AndroidRuntime(27380): Process: pl.holdapp.osw, PID: 27380
09-22 11:31:25.637: E/AndroidRuntime(27380): java.lang.NullPointerException
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.ParsePin.getParsePin(ParsePin.java:19)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.ParsePin.pinAllObjectsAsync(ParsePin.java:44)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.ParseObject.pinAllAsync(ParseObject.java:3320)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.ParseObject.pinAllInBackground(ParseObject.java:3417)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at pl.holdapp.osw.fragments.NewsFragment$2.done(NewsFragment.java:68)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.FindCallback.internalDone(FindCallback.java:45)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.FindCallback.internalDone(FindCallback.java:31)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.parse.Parse$6$1.run(Parse.java:917)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at android.os.Handler.handleCallback(Handler.java:733)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at android.os.Handler.dispatchMessage(Handler.java:95)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at android.os.Looper.loop(Looper.java:157)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at android.app.ActivityThread.main(ActivityThread.java:5356)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at java.lang.reflect.Method.invokeNative(Native Method)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at java.lang.reflect.Method.invoke(Method.java:515)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
09-22 11:31:25.637: E/AndroidRuntime(27380):    at dalvik.system.NativeStart.main(Native Method)

arg0 is not null and therefore I completely don't understand where that comes from.

回答1:

Apparently I didn't call Parse.enableLocalDatastore(context); before pinning.

来源：https://stackoverflow.com/questions/25970861/parseobject-pinallinbackground-results-with-nullpointerexception