Java Observable.hasChanged()
Syntax
Observable.hasChanged() has the following syntax.
public boolean hasChanged()
Example
In the following code shows how to use Observable.hasChanged() method.
/*from w w w. ja va 2 s . com*/
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)) {
watchedValue = value;
// mark as value changed
setChanged();
}
}
}
class MainObserver implements Observer {
public void update(Observable obj, Object arg) {
System.out.println("Update called");
}
}
public class Main{
public static void main(String[] args) {
ObservedObject watched = new ObservedObject("Original Value");
MainObserver watcher = new MainObserver();
watched.addObserver(watcher);
watched.setValue("New Value");
if(watched.hasChanged())
System.out.println("Value changed");
else
System.out.println("Value not changed");
}
}
The code above generates the following result.
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