AVQuery query = new AVQuery<>("Student");
query.whereEqualTo("lastName", "Smith");
query.findInBackground().subscribe(new Observer>() {
public void onSubscribe(Disposable disposable) {}
public void onNext(List students) {
// students 是包含满足条件的 Student 对象的数组
}
public void onError(Throwable throwable) {}
public void onComplete() {}
});