Quick summary


  • 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

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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.