Android : Parse : Java null exception

I have 2 user types , student and teachers. Need to write code to check if current user is student or teacher so i can start Activity(StudentActivity , TeacherActivity) and if user is not cashed i will send him to LoginActivity.

I have query that checks usernames from Parse Cloud and store it in array.

Now when I try to get ParseUser.getCurrentUser().getUsername and check if that username is in array I get Null Pointer Exception.

Here's Code .

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

    queryStudent();

    Intent intent;

    if(ParseUser.getCurrentUser() == null){
        intent = new Intent(MainActivity.this,LoginActivity.class);

    }
    else if(Arrays.asList(studentUsernames).contains(ParseUser.getCurrentUser().getUsername())){
        isStudent = true;

    }
    if (isStudent) {

        Intent intent1 = new Intent(this, StudentActivity.class);
        intent1.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        intent1.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
        startActivity(intent1);
    }

    if(!isStudent){

        Log.d("tag","user is teacher");
    }

}

And here is Query Student method:

public void queryStudent(){

        ParseQuery<ParseUser> query = ParseUser.getQuery();
        query.whereEqualTo("Type","student");
        query.findInBackground(new FindCallback<ParseUser>() {
            @Override
            public void done(List<ParseUser> users, ParseException e) {
                if(e == null){
                    //Success!
                    mUsers = users;
                    studentUsernames = new String[mUsers.size()];
                    int i = 0;
                    for(ParseUser user : mUsers){
                        studentUsernames[i] = user.getUsername();
                        i++;
                    }

                }else {
                    //Failed
                }
            }
        });
    }

Error : Unable to start activity ComponentInfo{com.aubihlms.aubih/com.aubihlms.aubih.MainActivity}: java.lang.NullPointerException: storage == null