observable

可觀察的類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()方法用于將給定的觀察者(obs)插入到此Observable對(duì)象的觀察者束中。

• 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()方法是一種非靜態(tài)方法，只能通過(guò)類對(duì)象訪問(wèn)，如果嘗試使用類名稱訪問(wèn)該方法，則會(huì)收到錯(cuò)誤消息。

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

  在添加觀察者時(shí)， addObserver()方法可能會(huì)引發(fā)異常。

Syntax:

句法：

protected void addObserver(Observer obs);

Parameter(s):

參數(shù)：

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

  Observer obs –表示要插入的觀察者對(duì)象。

Return value:

返回值：

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

該方法的返回類型為void ，不返回任何內(nèi)容。

Example:

例：

// Java program to demonstrate the example // of void addObserver(Observer obs) method of Observableimport 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 Methodpublic static void main(String args[]) {Observed observed = new Observed();Observers obs = new Observers();observed.addObserver(obs);observed.added();} }

Output

輸出量

Obs is added

翻譯自: https://www.includehelp.com/java/observable-addobserver-method-with-example.aspx

observable

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