Re: Backing Up Objects

From:

Piotr Kobzda <pikob@gazeta.pl>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 10 Jul 2007 14:25:14 +0200

Message-ID:

<f6vtre$kj1$1@inews.gazeta.pl>

Twisted wrote:

Of course, it doesn't *really* mutate a "String" value, in that your
String is seen by the compiler as a different type to, and not
assignable to, java.lang.String.

Of course, my String is different type. It simply allows to implement
the scenario described by the OP:

<sscce>
public class Test {
     public static void m(String[] args) {
         class String {
             java.lang.String value;
             public java.lang.String toString() { return value; }
         }
         String oldString = new String();
         String newString = oldString; // the OP's line (literally)
         oldString.value = "123";
         System.out.println(newString);
     }
}
</sscce>

On the other hand, there is another real way to mutate a String --
alter it when it's serialized, then deserialize it.

That way you cannot mutate the value of an existing String object. It
allows to create a new one only. To achieve similar effect, much easier
is to use a String's "copy constructor".

piotr