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// java.util.Observable -- an implementation of the Java Language Spec sec 21.7
// Written by Charles Briscoe-Smith; refer to the file LEGAL for details.
package java.util;
public class Observable {
private Vector observers=new Vector();
private boolean changed;
public void addObserver(Observer o)
{
if (! observers.contains(o))
observers.addElement(o);
}
public void deleteObserver(Observer o)
{
observers.removeElement(o);
}
public void deleteObservers()
{
observers.removeAllElements();
}
public int countObservers()
{
return observers.size();
}
public void notifyObservers()
{
notifyObservers(null);
}
public void notifyObservers(Object arg)
{
if (! hasChanged()) return;
for (Enumeration e=observers.elements(); e.hasMoreElements(); )
{
((Observer) e.nextElement()).update(this, arg);
}
clearChanged();
}
protected void setChanged()
{
changed=true;
}
protected void clearChanged()
{
changed=false;
}
public boolean hasChanged()
{
return changed;
}
}
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