What is the observer pattern?

• A one-to-many dependency between objects

– so that when one object changes state, all its dependents are notified and updated automatically.

• Observer distributes communication by introducing “observer” and “subject” objects

• Whenever the Subject changes, it broadcasts to all registered Observers that it has changed, and each Observer queries the Subject for that subset of the Subject’s state that it is responsible for monitoring.

What are the Java language features?

Which Java language feature supports the use of the Observer pattern?

Both object oriented and architecture-neutral , Java’s many features, enable the Observer pattern.

Object Oriented In Java, everything is an Object. Java can be easily extended since it is based on the Object model.

Architecture-neutral Java compiler generates an architecture-neutral object file format,

which makes the compiled code executable on many processors, with the presence of Java runtime system.

source