21.7

java.util.Observable

THE PACKAGE JAVA.UTIL

21.7.5

public void notifyObservers()

If this

Observable

 object has been marked as changed, this method causes all

observers to be notified with

null

 as the second argument; in other words, this

method is equivalent to:

notifyObservers(null)

21.7.6

public void notifyObservers(Object arg)

If this

Observable

 object has been marked as changed ( 21.7.9), this method

causes all observers to be notified with

arg

 as the second argument. An observer

is notified by calling its

update

 method ( 21.8.1) on two arguments: this

Observable

 object and

arg

. The mark on this object is then cleared ( 21.7.8).

21.7.7

protected void setChanged()

This

Observable

 object is marked as having been changed; the

hasChanged

method will now return

true

.

21.7.8

protected void clearChanged()

This

Observable

 object is marked as not having been changed; the

hasChanged

method will now return

false

.

21.7.9

public boolean hasChanged()

The result is true if and only if the

setChanged

 method has been called for this

Observable

 object more recently than either the

clearChanged

 method or the

notifyObservers

 method.

644