整合Scoreloop高分

Question

These two methods are called with no errors:

public void submitScore(long scoreValue) {
        final Score score = new Score((double) scoreValue, null);
        final ScoreController scoreController = new ScoreController(
            (RequestControllerObserver) new ScoreSubmitObserver());
        scoreController.submitScore(score);
    }

    private class ScoreSubmitObserver implements RequestControllerObserver {
        public void requestControllerDidFail
          (final RequestController requestController,
           final Exception exception) { }

        public void requestControllerDidReceiveResponse(
          final RequestController requestController) { }
    }

When I click a button and move to the `High Scores' activity, the following code is called:

// this is on the onCreate() method
List<Score> list = getScores();  // Highscores line 214
if(list.size() == 0) {
    scoreList.get(0).setText(
      "LIST WILL BE MORE THAN 0 SO THIS TEXT WILL NOT BE SEEN");
}

//Retrieving scores from Scoreloop server.
public List<Score> getScores() {

    //Create an instance of the controller
     ScoresController myScoresController = new ScoresController(null);
             // highscores line 244

     //Set the searchlist. Default is globalScoreSearchList
     myScoresController.setSearchList(SearchList.getBuddiesScoreSearchList());

     //Set the mode for the controller.
     myScoresController.setMode(2);

     //Set the range length of scores to be retrieved. Default is 25
     myScoresController.setRangeLength(20);

     //Make the request to the server
     myScoresController.loadRangeForUser(Session.getCurrentSession().getUser());

     List<Score> retrievedScores = myScoresController.getScores();
     return retrievedScores;
}

This code crashes the app with the below LogCat output:

 FATAL EXCEPTION: main
 java.lang.RuntimeException: Unable to start activity ComponentInfo{matt.lyons.bibletrivia.lite/matt.lyons.bibletrivia.lite.Highscores}: java.lang.IllegalArgumentException: observer parameter cannot be null
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
    at android.app.ActivityThread.access$600(ActivityThread.java:141)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:137)
    at android.app.ActivityThread.main(ActivityThread.java:5039)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:511)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
    at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.IllegalArgumentException: observer parameter cannot be null
    at com.scoreloop.client.android.core.controller.RequestController.<init>(SourceFile:159)
    at com.scoreloop.client.android.core.controller.ScoresController.<init>(SourceFile:187)
    at com.scoreloop.client.android.core.controller.ScoresController.<init>(SourceFile:168)
    at matt.lyons.bibletrivia.lite.Highscores.getScores(Highscores.java:244)
    at matt.lyons.bibletrivia.lite.Highscores.onCreate(Highscores.java:214)
    at android.app.Activity.performCreate(Activity.java:5104)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
    ... 11 more

I commented in the line numbers in the code. I am not sure what the IllegalArgumentException is in the LogCat. My question is how to fix this error.

Answer 1

You create a new ScoresController with a null parameter (first line in getScores()). What happens then, according to the stack trace you provided, is that this constructor calls another constructor in the same class, which tries to create a RequestController. I suspect that you are forwarding the null parameter to the RequestController constructor, which does not accept a null value for the observer parameter.

IllegalArgumentException usually denotes a bug, where a method receives a parameter it is not supposed to deal with.