Copyright (c) SEMM NL All rights reserved.
Author : Paul Hamaker. Part of JavaLessons.com

OurBean calls the actionPerformed method of classes that have been added as actionListeners.

An instance can be added to a java.util.Vector for that purpose :

Naturally, there's also a method for removing a listener.

When the bean is clicked, it traverses the list of listeners and calls each listener's actionPerformed method .

First it creates an ActionEvent.

( OurBean.this because we don't want to pass the MA instance's reference as event source )

And locks the Vector, als, for itself in this block, so meanwhile other threads cannot change the Vector's contents ! ( More on this in the Threads lessons )

Because nextElement returns a reference of type Object, it has to be cast to ActionListener,....

so we can call actionPerformed :

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The preferred way to deploy beans is in a package, zipped into a .jar file.

There has to be a manifest file inside the jar file in a directory META-INF, called MANIFEST.MF .

Your builder tool will probably have a means to create a .jar file and generate a manifest file.

On the other hand, you could create it with the SDK tool : jar.exe .

From the directory that contains the ourbeans directory :

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NOTES

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Reflection :
addMouseListener
removeMouseListener
addWindowListener
removeWindowListener etc.

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ANY class containing set/get-methods+data, add/remove....Listener methods, implementing Serializable, can be used as a bean.

We've chosen Canvas, because we wanted to use a visual bean.

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When there are many listeners, the approach shown is probably not okay, because the Vector stays locked.

In that case it's better to make a clone of the Vector and use that to deal with the listeners, keeping the original Vecor unoccupied.
  Vector clohn = als.clone( ) ;

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Vector's initial size is for 5 elements, but it can grow by 2 elements each time, if necessary.

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Transient means : will not be saved or restored, which would be of no use, since listeners (un)register during run-time.

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