Java 中的 this 和 super



this

目前類的執行個體. 可被用作引用變量(第6行) 或者 方法 (第10行).

1   class Numbers {
 2      private int aNumber = 42;
 3
 4      public int returnANumber() 
 5      {
 6         return this.aNumber;
 7      }
 8      public int returnANumber(int intIn) 
 9      {
10         return (intIn * this.returnANumber()); 
11      }
12
13      public static void main(String[] args) {
14
15         Numbers numberTest = new Numbers();
16  
17         System.out.println("The Number is " +
             numberTest.returnANumber() );
18         //output is: The Number is 42
19         System.out.println("The Number is " + 
             numberTest.returnANumber(2) );    
20         //output is: The Number is 84   
21      }    
22   }

           

super

用于特指引用父類方法

class Cat {
   public String name; 
   public Cat() {name = "no nameIn";}
   public Cat(String nameIn) {name = nameIn;}
   public String getName() { 
       return(name + " the Cat"); 
   }           
}          


class Himalayan extends Cat {  
   public Himalayan() {} 
   public Himalayan(String nameIn) {
       name = nameIn;
   }
   public String getName() { 
       return (name + " the Himalayan"); 
   }
   public String getNameAsCat() { 
       return super.getName(); 
   }
   
   public static void main(String[] args) {


      Himalayan cappuccino = new Himalayan("Cappuccino");
 
      System.out.println("The Himalayan name is " + 
        cappuccino.getName() );
      //output is: The Himalayan name is 
      //  Cappuccino the Himalayan
	  
      System.out.println("The Cat name is "
        + cappuccino.getNameAsCat() );    
      //output is: The Cat name is 
      //  Cappuccino the Cat   
   }
}