Examples of Design Patterns used in JDK [duplicate]

Question

Possible Duplicate:
Examples of GoF Design Patterns

At an interview a while back I was asked for some examples of Design Patterns within the JDK.

Off the top of my head I was able to identify

Flyweight - as used in the String pool Singleton - in java.lang.Runtime Iterator - as used on Collections classes

Not that many.

What are the other good examples of Design Patterns as used in the JDK?

Answer 1

Observer interfaces, you have them out-of-the-box.

For a complete answer, read this: Examples of GoF Design Patterns in Java's core libraries