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toString method

 
venkatesh pendharkar
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hi
i was trying th following code:
class D
{
void met()
{
Byte b=new Byte("111");
System.out.println(b.toString()==b.toString());
}

public static void main(String[] args)
{
D d=new D();
d.met();
}
This will print "false" as "==" method compares memory address of objects & toString() returns a String object representing the primitive value.
But in the above code ;instead of Byte b=new Byte("111"); we write it as Boolean b=new Boolean("true"); then we get output as "true".

Why is it so that if we take boolean object the "==" method returns true but for any other wrapper object it returns "false".
 
Keith Lynn
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This is from the API docs for Boolean.

toString

public static String toString(boolean b)

Returns a String object representing the specified boolean. If the specified boolean is true, then the string "true" will be returned, otherwise the string "false" will be returned.

Parameters:
b - the boolean to be converted
Returns:
the string representation of the specified boolean
Since:
1.4



This is from the API docs for Byte.

toString

public String toString()

Returns a String object representing this Byte's value. The value is converted to signed decimal representation and returned as a string, exactly as if the byte value were given as an argument to the toString(byte) method.


toString

public static String toString(byte b)

Returns a new String object representing the specified byte. The radix is assumed to be 10.


So the toString() method of Byte returns a new String object representing the Byte, but a Boolean object will return a reference to either the String literal "true" or the String literal "false".
 
venkatesh pendharkar
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Thanks a lot Keith for your help.Actually I am preaparing for SCJP exam & i came across this question in one of the Mocks.
Hey if possible can you send me any links which are good for SCJP preaparation
 
It is sorta covered in the JavaRanch Style Guide.
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