observable

可觀察的類deleteObserver()方法 (Observable Class deleteObserver() method)

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

  deleteObserver()方法在java.util包中可用。

• deleteObserver() method is used to remove the given observer (obs) from the set of observers of this Observable object.

  deleteObserver()方法用于從此Observable對象的觀察者集中刪除給定的觀察者。

• deleteObserver() 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.

  deleteObserver()方法是一個非靜態(tài)方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。

• deleteObserver() method does not throw an exception at the time of deleting an observer.

  deleteObserver()方法在刪除觀察者時不會引發(fā)異常。

Syntax:

句法：

public void deleteObserver(Observer obs);

Parameter(s):

參數(shù)：

• Observer obs – represents the observer to be removed from the set.

  Observer obs –代表要從集合中刪除的觀察者。

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 deleteObserver(Observer obs) method of Observableimport java.util.*;// Implement Observers class class Observers_1 implements Observer {public void update(Observable obj, Object ob) {System.out.println("Obs1: ");} }class Observers_2 implements Observer {public void update(Observable obj, Object ob) {System.out.println("Obs2: ");} }// Implement Observed Class class Observed extends Observable {// Function callvoid deleteObs() {setChanged();// By using notifyObservers() method is // to notify all the observers that are// implementednotifyObservers();} }public class DeleteObservers {// Implement Main Methodpublic static void main(String args[]) {Observed observed = new Observed();Observers_1 obs1 = new Observers_1();Observers_2 obs2 = new Observers_2();observed.addObserver(obs1);observed.addObserver(obs2);// By using countObservers() method is// to return the number of observers // in this objectint count_obs = observed.countObservers();System.out.println("observed.countObservers(): " + count_obs);observed.deleteObs();// By using deleteObserver() method is used// delete the given observer if existsobserved.deleteObserver(obs2);count_obs = observed.countObservers();System.out.println("observed.deleteObserver(obs2): " + count_obs);observed.deleteObs();} }

Output

輸出量

observed.countObservers(): 2 Obs2: Obs1: observed.deleteObserver(obs2): 1 Obs1:

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

observable

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