Re: Strings...immutable?

From:

John T <printdude1968@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 19 Mar 2007 01:23:30 GMT

Message-ID:

<mClLh.12151$PV3.125215@ursa-nb00s0.nbnet.nb.ca>

Lew wrote:

Joshua Cranmer wrote:

2. This should return true, using the Sun JVM:

public class Foo {
    final static String bar1 = "Hello";
    final static String bar2 = "Hello";

    public static boolean equal() {
        return bar1 == bar2;
    }
}

It must return true, given anyone's JVM.

* Literal strings within the same class (??8) in the same package (??7)
represent references to the same String object (??4.3.1).
* Literal strings within different classes in the same package
represent references to the same String object.
* Literal strings within different classes in different packages
likewise represent references to the same String object.
* Strings computed by constant expressions (??15.28) are computed at
compile time and then treated as if they were literals.
* Strings computed by concatenation at run time are newly created and
therefore distinct.

-- Lew

Why is it that every time I ask a seemingly harmless question, it turns
out to be a debate/discussion that far surpasses my original question? :-)

Not that there is anything wrong with what's being talked about now but
my question was answered 3 or 4 replies after my original post... so now
we are talking about garbage collection?

After doing a bit more studying, I've learned that it's the contents of
the string object that are subject to change, not the string itself,
hence the idea/rule that strings are immutable. Is this a correct
interpretation or do I need to go back to the books again?