observable

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

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

  countObservers()方法在java.util包中可用。

• countObservers() method is used to count the number of observers exists in this Observable.

  countObservers()方法用于計算此Observable中存在的觀察者的數(shù)量。

• countObservers() 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.

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

• countObservers() method does not throw an exception at the time of counting the observer.

  在計數(shù)觀察者時， countObservers()方法不會引發(fā)異常。

Syntax:

句法：

public int countObservers();

Parameter(s):

參數(shù)：

• It does not accept any parameter.

  它不接受任何參數(shù)。

Return value:

返回值：

The return type of the method is int, it gets the number of observers in this Observable.

方法的返回類型為int ，它獲取此Observable中的觀察者數(shù)量。

Example:

例：

// Java program to demonstrate the example // of int countObservers() 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 countObs() {setChanged();// By using notifyObservers() method is // to notify all the observers that are// implementednotifyObservers();} }public class CountObservers {// 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.countObs();} }

Output

輸出量

observed.countObservers(): 2 Obs2: Obs1:

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

observable

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