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String Pool Vs String new operator

kri shan
Ranch Hand

Joined: Apr 08, 2004
Posts: 1371
String str1 = "how are you";

String str2 = new String("how are you");

Whether String Str1 will refer string poll for Str1 exists in the pool or not. If exists, then this will return the reference, If not exist, will it create new object like new operator ?
String str2 never refer the string pool because it is created by new operator(creates new String object in the heap). Which one is memory efficient ?
Paul Clapham
Bartender

Joined: Oct 14, 2005
Posts: 18541
    
    8

Is it more memory-efficient to use an existing object from a pool, or to create a new object which is a copy of one from the pool?
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 38057
    
  22
Have you seen what it says in the API about that String constructor?
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19655
    
  18

Obviously the first statement is more memory efficient. Both use the same String from the String pool, but the first one uses only this object; the second one makes an exact copy of it and uses that. With String being immutable, that's completely superfluous. That's why the API discourages using that constructor, as Campbell's link indicates.


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It is sorta covered in the JavaRanch Style Guide.
 
subject: String Pool Vs String new operator
 
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