Java中的default关键字

//DefaultIntf.java  
public interface DefaultIntf { 
    default void printHello(){ 
        System.out.println("Hello"); 
    } 
     
    void printHi(); 
} 
 
//Default.java  
public class Default implements DefaultIntf { 
    /* 
    //@Override 
    public void printHello(){ 
        System.out.println("Hello World!"); 
    } 
    */ 
    //@Override 
    public void printHi() { 
        System.out.println("Hi"); 
    } 
 
    public static void main(String[] args){ 
        Default d1 = new Default(); 
        d1.printHello(); 
    } 
}