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Java.util.Observable.deleteObservers() Method
Description
The java.util.Observable.deleteObservers() method clears the observer list. This object will no longer have any observers.
Declaration
Following is the declaration for java.util.Observable.deleteObservers() method
public void deleteObservers()
Parameters
NA
Return Value
NA
Exception
NA
Example
The following example shows the usage of java.util.Observable.deleteObservers() method.
package com.tutorialspoint; import java.util.Observable; import java.util.Observer; class ObservedObject extends Observable { private String watchedValue; public ObservedObject(String value) { watchedValue = value; } public void setValue(String value) { // if value has changed notify observers if(!watchedValue.equals(value)) { System.out.println("Value changed to new value: "+value); watchedValue = value; // mark as value changed setChanged(); // trigger notification notifyObservers(value); } } } public class ObservableDemo implements Observer { public String name; public ObservableDemo(String name) { this.name = name; } public static void main(String[] args) { // create watched and watcher objects ObservedObject watched = new ObservedObject("Original Value"); // watcher object listens to object change ObservableDemo watcher1 = new ObservableDemo("Watcher1"); ObservableDemo watcher2 = new ObservableDemo("Watcher2"); // trigger value change watched.setValue("Value before addObserver"); // add observer to the watched object watched.addObserver(watcher1); watched.addObserver(watcher2); // trigger value change watched.setValue("Value after addObserver"); // delete all observers watched.deleteObservers(); // trigger value change watched.setValue("Value after deleteObservers"); } public void update(Observable obj, Object arg) { System.out.println(name+" called with Arguments: "+arg); } }
Let us compile and run the above program, this will produce the following result −
Value changed to new value: Value before addObserver Value changed to new value: Value after addObserver Watcher2 called with Arguments: Value after addObserver Watcher1 called with Arguments: Value after addObserver Value changed to new value: Value after deleteObservers
java_util_observable.htm
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