toString()

[Ram Murthy]

1: Byte b1 = new Byte("127");
2:
3: if(b1.toString() == b1.toString())
4: System.out.println("True");
5: else
6: System.out.println("False");

A) Compilation error, toString() is not avialable for Byte.
B) Prints "True".
C) Prints "False".

The o/p is C.

Why <<b1.toString() == b1.toString()>> not true ??

Thanks,
JP

[Barry Gaunt]

Each call to the toString() method returns a new distinct String object. Two distinct objects are not "==" to each other.

[Ram Murthy]

I tried the below code ...

Byte b1 = new Byte("127");
System.out.println(b1.toString());
System.out.println(b1.toString());

Both the SOP's returned 127, I don't see what is distinct here ??

Regards,
JP

[Kevin Lam]

But when you compare with ==, it compares the "reference address"

Although two Strings contains the same letters, but it is two different objects, hence two different addresses.

If you compare them with equals(), that will return you true because that compares the content of the two strings instead of the address.

Hope this helps

Kev

[Abdulla Mamuwala]

Ravi,

Each call to the toString() method returns a new distinct String object. Two distinct objects are not "==" to each other.

What Barry meant above is that the "==" checks for reference equality and not for equality of what the Byte objects hold in this case the value 127.
Let's look at the following code diagramatically,

Byte b1 = new Byte("127");
A object is created on the heap with reference A0

  
b1---------------------------------->127(object on heap)
[Byte]            A0                 [Byte]

System.out.println(b1.toString());
The code above will create a new object on the heap, with reference A2

  
b1---------------------------------->127(object on heap)
[String]            A2              [String]

System.out.println(b1.toString());
The code above will create a new object on the heap, with reference A3

  
b1---------------------------------->127(object on heap)
[String]            A3              [String]

As you can see the references A2 and A3 are not the same, therefore '==' returns false.

[Ram Murthy]

Thanks I got it.