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Java Observable addObserver() Method with Example
Observable Class addObserver() method: Here, we are going to learn about the addObserver() method of Observable Class with its syntax and example.
Submitted by Preeti Jain, on March 02, 2020
Observable Class addObserver() method
- addObserver() method is available in java.util package.
- addObserver() method is used to insert the given observer (obs) to the bundles of observers for this Observable object.
- 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() method may throw an exception at the time of adding an observer.
Syntax:
protected void addObserver(Observer obs);
Parameter(s):
- Observer obs – represents the observer object to be inserted.
Return value:
The return type of the method is void, it returns nothing.
Example:
// 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
Obs is added