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Interfaces, GUIs, and Applets
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CS 161 - Java |
In Java applications that use a graphical user interface (GUI)
or other event driven styles you see lots of:
...
Something s = new Something();
...
UserInterfaceComponent c = new UserInterfaceComponent();
c.addSomethingListener(s);
...
and, in the implementation of the Something.java class source, you
would see
public class Something
implements SomethingListener {
...
public void somethingDone() {
...
}
...
}
where SomethingListener is one of a number of interfaces and
somethingDone is a method that the somethingListener
interface defines.
The SomethingListener interface is a contract that classes agree to
abide by by saying they implement the interface.
The UserInterfaceComponents don't have code that refers to the SomeThing
class (or any other application specific class that you write); they
simply treat all such classes as SomethingListener objects.
This allows the UserInterfaceComponent classes to be independent
of application specific classes.
