写一下观察者模式java代码
时间: 2023-11-29 21:15:17 浏览: 28
好的,以下是观察者模式的Java代码示例:
// Subject.java
import java.util.ArrayList;
import java.util.List;
public class Subject {
private List<Observer> observers = new ArrayList<>();
private int state;
public int getState() {
return state;
}
public void setState(int state) {
this.state = state;
notifyAllObservers();
}
public void attach(Observer observer) {
observers.add(observer);
}
public void notifyAllObservers() {
for (Observer observer : observers) {
observer.update();
}
}
}
// Observer.java
public abstract class Observer {
protected Subject subject;
public Observer(Subject subject) {
this.subject = subject;
subject.attach(this);
}
public abstract void update();
}
// BinaryObserver.java
public class BinaryObserver extends Observer {
public BinaryObserver(Subject subject) {
super(subject);
}
@Override
public void update() {
System.out.println("Binary String: " + Integer.toBinaryString(subject.getState()));
}
}
// OctalObserver.java
public class OctalObserver extends Observer {
public OctalObserver(Subject subject) {
super(subject);
}
@Override
public void update() {
System.out.println("Octal String: " + Integer.toOctalString(subject.getState()));
}
}
// HexObserver.java
public class HexObserver extends Observer {
public HexObserver(Subject subject) {
super(subject);
}
@Override
public void update() {
System.out.println("Hex String: " + Integer.toHexString(subject.getState()));
}
}
// Main.java
public class Main {
public static void main(String[] args) {
Subject subject = new Subject();
new BinaryObserver(subject);
new OctalObserver(subject);
new HexObserver(subject);
System.out.println("First state change: 15");
subject.setState(15);
System.out.println("Second state change: 10");
subject.setState(10);
}
}
希望能对您有所帮助。