Java8 new features - the default method

What is?

　　It is the interface can have a default implementation, but do not need to achieve its implementation class method.

 

how to use?

　　In the former method plus default, static methods directly write the default implementation

 

1  / * 
2  * default method
 . 3   * / 
. 4  public  class DefaultMethod {
 . 5      public  static  void main (String [] args) {
 . 6          VO = VO new new VO ();
 . 7          vo.doSome ();
 . 8          VO.doSomeTwo () ;
 . 9      }
 10  }
 . 11  
12 is  interface Operate {
 13 is      default  void doSome () {
 14          System.out.println ( "original version" );
 15      }
 16  
. 17      static void doSomeTwo () {
 18 is          System.out.println ( "abstract original version" );
 . 19      }
 20 is  }
 21 is  
22 is  class DB the implements Operate {
 23 is  
24      @Override
 25      public  void doSome () {
 26 is          System.out.println ( "first a rewritten version " );
 27          . Operate Super .doSome ();
 28      }
 29  
30      public  static  void doSomeTwo () {
 31 is          System.out.println (" first abstract rewritten version " );
 32         Operate.doSomeTwo ();
 33 is      }
 34 is  }
 35  
36  class VO the extends DB {
 37 [  
38 is      @Override
 39      public  void doSome () {
 40          System.out.println ( "second rewritten version" );
 41 is          DB = DB new new DB ();
 42 is          db.doSome ();
 43 is      }
 44 is  
45      public  static  void doSomeTwo () {
 46 is          System.out.println ( "second abstract rewritten version" );
 47          DB.doSomeTwo ();
 48     }
49 
50 }

 

what is the benefit?

　　When prevent modification interface, the interface class needs to change all modifications