Strings

[sabah ammar]

Hi ,
I am not very sure how do strings perform in memory when == is tested with attributes.
please explain whatever u can . thanks

 if("String".trim() == "String".trim()) 
    System.out.println("Equal"); 
else 
    System.out.println("Not Equal");
 

if( "STRING".toUpperCase() == "STRING") 
    System.out.println("Equal"); 
else 
    System.out.println("Not Equal");
 

if("String".substring(0) == "String") 
    System.out.println("Equal"); 
else 
    System.out.println("Not Equal");
 

if("String".substring(0,6) == "String") 
    System.out.println("Equal"); 
else 
    System.out.println("Not Equal");
 
if("String".replace('t','t') == "String") 
    System.out.println("Equal"); 
else 
    System.out.println("Not Equal");
 
if("String".replace('T','t') == "String") 
    System.out.println("Equal"); 
else 
    System.out.println("Not Equal");
 
 

[Mike Gershman]

The String methods create a new, unique String only when they change the string they are called on.

"String".trim() does not change the string, so you get back a reference to "String" in the string literal pool.

All of your specific examples have this same effect.

== checks for the same object, so comparing two references to the same string in the string literal pool returns true