我定义了以下两个类:
public abstract class Subject {
private ArrayList<ClockObserver> clockObserverList = new ArrayList<ClockObserver>();
public void attach(ClockObserver clockObserver) {
// begin-user-code
// TODO Auto-generated method stub
clockObserverList.add(clockObserver);
// end-user-code
}
public void dettach(ClockObserver clockObserver) {
// begin-user-code
// TODO Auto-generated method stub
clockObserverList.remove(clockObserver);
// end-user-code
}
protected void notify() {
// begin-user-code
// TODO Auto-generated method stub
for(int i= 0; i < clockObserverList.size(); i++)
{
clockObserverList.get(i).update();
}
// end-user-code
}
}
和
public class SystemClock extends Subject {
private int hour;
private int minute;
private int second;
public void setTime(int hour, int minute, int second) {
this.hour = hour;
this.minute= minute;
this.second = second;
notify();
}
public ClockTime getTime() {
ClockTime clockTime = new ClockTime();
clockTime.hour = this.hour;
clockTime.minute = this.minute;
clockTime.second = this.second;
return clockTime;
}
public void displayTime() {
System.out.println("Time is :" + this.hour + ":" + this.minute + ":" + this.second);
}
}
我在通知函数中遇到以下错误:
Multiple markers at this line
- Cannot override the final method from Object
- overrides java.lang.Object.notify
- Cannot reduce the visibility of the inherited method from
即使我将其可见性从 protected 更改为公开,我仍然遇到以下错误:
Multiple markers at this line
- Cannot override the final method from Object
你能帮我看看问题出在哪里吗?
最佳答案
在 Java 中,每个类都隐式扩展 Object
类,该类定义了一个名为 notify
的方法。因此,如果您在类中创建一个 notify
方法,编译器会认为您试图重写 Object.notify
方法,但事实显然并非如此。
只需重命名您的方法 notify
就可以了。
关于java - 无法降低对象继承方法的可见性,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/29448108/