Android - 无法刷新ListView

Question

我试图用一堆字符串来更新我的ListView，但现在它是如何工作的，当我调用updateClassesList（）方法它没有更新ListView。我也搞乱了onResume（），这也让它消失了。建议表示赞赏！

private ArrayAdapter<String> classListAdapter;
private List<String> classes;

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

    mClassesListView = (ListView) findViewById(R.id.classesListView);
    mEmptyListTextView = (TextView) findViewById(R.id.emptyListTextView);
    mProgressBar =(ProgressBar) findViewById(R.id.progressBar);
    mProgressBar.setVisibility(View.INVISIBLE);

    mClassesListView.setAdapter(classListAdapter);

    updateClassesList();
}

private void updateClassesList() {
    if(isNetworkAvailable()) {
        classes = new ArrayList<String>();

        toggleRefresh();
        ParseUser currentUser = ParseUser.getCurrentUser();
        if (currentUser == null) {
            navigateToLogin();
        } else {
            Log.i(TAG, currentUser.getUsername());
        }

        ParseQuery<ParseObject> query = ParseQuery.getQuery("Classes");
        if (currentUser != null) {
            query.whereEqualTo("username", currentUser.getUsername());
        }
        query.orderByAscending("createdAt");
        query.findInBackground(new FindCallback<ParseObject>() {
            public void done(List<ParseObject> classesList, ParseException e) {
                toggleRefresh();
                if (e == null) {
                    Log.d("Classes", "Retrieved " + classesList.size() + ": " + classesList);

                    for (int i = 0; i < classesList.size(); i++) {
                        classes.add(classesList.get(i).getString("classTitle") + "");
                        Log.d(TAG, classesList.get(i).getString("classTitle"));
                    }

                } else {
                    Log.d("Classes", "Error: " + e.getMessage());
                }
            }
        });

        classListAdapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, classes);

        mClassesListView.setAdapter(classListAdapter);
    }
    else{
        Toast.makeText(this,"No network connection", Toast.LENGTH_SHORT).show();
    }
}