Understanding Byte and == Op

[Ethan Bosco]

I am unable to understand the output

  
class XXXXX {
public static void main ( String args [ ] ) {
 Byte b1 = new Byte("127");
Byte b2 = new Byte("2");
 
 if(b1.toString() == b1.toString())
       System.out.println("True");
 else
       System.out.println("False");
 
if(b2.toString() == b2.toString())
       System.out.println("True");
 else
       System.out.println("False");
 
}
}

Output :- False True

[marc weber]

I compiled and ran your code using 1.5.0, and got "False False" as output. (The toString method is creating new Strings at runtime, so these are different references.)

Can you verify your output?
[ November 01, 2004: Message edited by: marc weber ]

[Ethan Bosco]

thanks for taking the time to answer, I am also using 1.5 but I am getting the output that I had mentioned - what output are you getting and and can u explain it ? thanks

[marc weber]

The output I get is "False False." The toString method of Byte is returning a new runtime String instance each time it's called, and == is a shallow comparision of references.

b1.toString() is one reference, and b1.toString() is another, so the == comparison returns false. (These are not literals in the pool.)

Of course, the deeper equals() comparison returns true.

class XXXXX {
  public static void main ( String args [ ] ) {
    Byte b1 = new Byte("127");
    Byte b2 = new Byte("2");
 
    //shallow == comparison returns false...
    if(b1.toString() == b1.toString())
      System.out.println("b1 == is true");
    else
      System.out.println("b1 == is false");
 
    if(b2.toString() == b2.toString())
      System.out.println("b2 == is true");
    else
      System.out.println("b2 == is false");
 
    //deep equals() comparison returns true...
    if( (b1.toString()).equals(b1.toString()) )
      System.out.println("b1 equals is true");
    else
      System.out.println("b1 equals is false");
 
    if( (b2.toString()).equals(b2.toString()) )
      System.out.println("b2 equals is true");
    else
      System.out.println("b2 equals is alse");
  }
}

[Hai Le]

i have the same thought with marc weber and my compiler tell me that the result is "falsefalse"

[Barry Gaunt]

"thirxtymilk" please read our JavaRanch Naming Policy and change your displayed name to conform with it.

Thanks
-Barry

[Barry Gaunt]

Same code without the redundant if stuff:

 class XXXXX {
public static void main ( String args [ ] ) {
       Byte b1 = new Byte("127");
       Byte b2 = new Byte("2");
       System.out.print(b1.toString() == b1.toString());
       System.out.println(b2.toString() == b2.toString());
   }
} 

Prints "falsefalse" on Java 1.5.