The syntax for declaring an interface
public interface InterfaceName { type CONSTANT_NAME = value; // declares a const field returnType methodName([parameterList]); // declares a method }
- interfaces can not contain code
- all methods are automaticly declared as public, abstrace.
- all fields are automaticly declared public, static, and final.
- interface methods can't be static.
An example of an interface:
public interface Products { int ADMIN = 1; int USER = 2; bollean addProduct(Product product); bollean deleteProduct(Product product); }
How to implement and interface
public class MyProducts implements Products { bollean addProduct(Product product) { if (user != ADMIN ) … code goes here } bollean deleteProduct(Product product) { … code goes here } }
How to inherit a class and implement an interface
public class SubclassName extends SuperClassName implements Interface1[, interface2] { }