萌新求大神帮助Java读数据问题

LCQuery query = new LCQuery<>("Todo");
query.selectKeys(Arrays.asList("title", "content"));
query.getFirstInBackground().subscribe(new Observer() {
public void onSubscribe(Disposable disposable) {}
public void onNext(LCObject todo) {
String title = todo.getString("title"); // √
String content = todo.getString("content"); // √
String notes = todo.getString("notes"); // 会报错
}
public void onError(Throwable throwable) {}
public void onComplete() {}
});

用这段的时候Oberver()那段报错
error: type Observer does not take parameters
query.getFirstInBackground().subscribe(new Observer>() {

这个是什么问题呀 求解答！先跪谢了！