observable

可观察的类addObserver()方法 (Observable Class addObserver() method)

• addObserver() method is available in java.util package.

  addObserver()方法在java.util包中可用。

• addObserver() method is used to insert the given observer (obs) to the bundles of observers for this Observable object.

  addObserver()方法用于将给定的观察者(obs)插入到此Observable对象的观察者束中。

• addObserver() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  addObserver()方法是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

• addObserver() method may throw an exception at the time of adding an observer.

  在添加观察者时， addObserver()方法可能会引发异常。

Syntax:

句法：

    protected void addObserver(Observer obs);

Parameter(s):

参数：

• Observer obs – represents the observer object to be inserted.

  Observer obs –表示要插入的观察者对象。

Return value:

返回值：

The return type of the method is void, it returns nothing.

该方法的返回类型为void ，不返回任何内容。

Example:

例：

// Java program to demonstrate the example 
// of void addObserver(Observer obs) method of Observable
import java.util.*;
// Implement Observers class 
class Observers implements Observer {
public void update(Observable obj, Object ob) {
System.out.println("Obs is added");
}
}
// Implement Observed Class
class Observed extends Observable {
void added() {
setChanged();
notifyObservers();
}
}
public class Main {
// Implement Main Method
public static void main(String args[]) {
Observed observed = new Observed();
Observers obs = new Observers();
observed.addObserver(obs);
observed.added();
}
}

Output

输出量

Obs is added

翻译自: https://www.includehelp.com/java/observable-addobserver-method-with-example.aspx

observable