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。

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

  在添加觀察者時， addObserver()方法可能會引發異常。

Syntax:

句法：

    protected void addObserver(Observer obs);

Parameter(s):

參數：

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

  Observer obs –表示要插入的觀察者對象。

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

輸出量

Obs is added

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

observable