java - 空指针异常 : Attempt to invoke virtual method on a null object reference

Question

获取空指针异常请帮忙

 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_appbar);

    toolbar=(Toolbar) findViewById(R.id.app_bar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setDisplayShowHomeEnabled(true);

    NavFragment drawerFragment = (NavFragment)
            getSupportFragmentManager().findFragmentById(R.id.nav_frag);
    drawerFragment.setUp(R.id.nav_frag, (DrawerLayout) findViewById(R.id.drawerLayout), toolbar);
    listEvents= new ArrayList<>();



    Parse.enableLocalDatastore(this);
    Parse.initialize(this, "xxxxxxxxxxxxxxxxxxxxxxx", "xxxxxxxxxxxxxxxxxxx");

    //TEST PARSE
    final TextView t =(TextView) findViewById(R.id.textView);
    ParseQuery<ParseObject> query = ParseQuery.getQuery("Test");
    //query.whereEqualTo("playerName", "Dan Stemkoski");
    query.findInBackground(new FindCallback<ParseObject>() {
        public void done(List<ParseObject> eventList, ParseException e) {
            if (e == null) {
                Log.d("Events", "Retrieved " + eventList.size() + " Events");

                for (int i = 0; i < eventList.size(); i++) {
                    Events events = new Events();
                    events.setTitle((String) eventList.get(i).get("teststr"));
                    events.setId((String) eventList.get(i).get("id"));
                    listEvents.add(events);
                }
            } else {
                Log.d("score", "Error: " + e.getMessage());
            }
        }
    });

    eventAdapter.setEventList(listEvents);


    eventsList=(RecyclerView)findViewById(R.id.list_events);
    eventsList.setLayoutManager(new LinearLayoutManager(this));
    eventAdapter= new EventAdapter(this);
    eventsList.setAdapter(eventAdapter);




}

这是我遇到异常的地方.. 日志猫:

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.squaredbytes.eventlane.EventAdapter.setEventList(java.util.ArrayList)' on a null object reference

Answer 1

您尝试在实例化 eventAdapter 之前调用它的方法。