Java 8 new Features-Interface definition enhancements

In order to solve the existing interface in the method is insufficient, add a new method to the original interface , n multi-implementation class under the interface also need to rewrite the method of the problem! JAVA8 introduces an interface definition enhancement concept!

Java8 broke the method definition of the original interface: Public, abstract

• Default Method：
  • Java 8 also allows us to add a non-abstract method implementation to the interface, just using the default keyword , which is also called the extension method.
  • When the interface is implemented, the default extension method can be used directly on subclasses, which are used in a manner similar to non-abstract member methods in abstract classes.
  • However, the extension method is not able to overload the method in Object. For example: toString, equals, hashcode cannot be overloaded in the interface.
  • For example:

  • Interfaceimassage{ Public Abstract voidPrint ();//This is the original definition of the interface.     Public default voidFun () {//define a common method in the interfaceSystem.out.println ("Use the default keyword to define the common method in the interface!" "); }}classMessageimplImplementsimassage{@Override Public voidprint () {System.out.println ("The implementation class of the interface! "); }}　　　

• • Test:

     public  class   Newinterface { public  Span style= "color: #0000ff;" >static  void   main (string[] args) {Imassa        GE massage  = new   Messageimpl ();  //  Normal method implementations call   Massage.print ();  //  Call the normal method in the interface   Massage.fun (); }}

• • Results:
• Static methods
  • The other is to define a static method in the interface, using the static keyword
  • For example:

    Interface   imassage{    publicstaticvoid  funstatic () {        SYSTEM.OUT.PRINTLN ("Use static keyword to define static method in Interface");}    }

  • Called in the same way as a normal static method call

  •    // call the static method   defined in the interface Imassage.funstatic ();

Java 8 new Features-Interface definition enhancements