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From: markspace <markspace@nospam.nospam>
Newsgroups: comp.lang.java.programmer
Subject: Re: how actually string store in java machine
Date: Wed, 26 Mar 2014 08:32:42 -0700
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On 3/25/2014 7:37 PM, Roedy Green wrote:
> On Tue, 25 Mar 2014 20:31:50 +0100, Jan Burse <janburse@fastmail.fm>
> wrote, quoted or indirectly quoted someone who said :
>
>>
>> http://stackoverflow.com/questions/16690815/shared-constant-pool
>
> I was under the impression all string constants lived in the same pool
> along with the interned strings. That would imply a shared constant
> pool since day 1.  Have I had this wrong since Java 1.0?
>


Yes, I'm pretty sure you've been wrong if that's what you thought.  Each 
class has its own pool of strings.  If you have a class with a constant 
string:

   String a = "a";
   String b = "a";

The constant "a" is only stored once, and a==b will be true.  But that's 
only for a single class file.  Outside of the class file, each string is 
unique and a different object.  I don't think any implementations of the 
JVM called String.intern() for each constant string read in each class file.

And certainly if you read a string from a file or the network, the VM 
does not call String.intern() for you.  That would be silly.