Java: Interfaces

Quick summary

Interfaces:

• Interfaces can’t be instantiated
• Interfaces have methods with no bodies (no {})
• Subclasses implement interfaces (as many as they want)
• Subclasses must implement all the interface’s methods
• Interfaces standardize methods and fields for all subclasses
• All fields are final static
• The default access for an interface is protected
• The default access for an interface’s methods is public

Eclipse example: Interfaces

Detailed description

An interface is a class that has methods with no bodies. It is intended to be implemented by another class that will insert their own values for the methods. It’s a way of formalizing a class that will have a lot of subclasses, when you want all the subclasses to standardize on common strings and methods.