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Message:

Strings are very special objects

Posted by Ivan Porty on May 26, 2000 at 3:21 AM

> Why is the String class from Sun final?
> Wouldn't it be nice to create a class which could
> extend the String class? Or am I going about this OO
> thing the wrong way?

> Thanks, Dan

Good Day, Mr. Cranmer!

Strings are very special objects in Java, because they were initially,
by design, highly optimized. That's very important, because of String's
high importance. Everybody uses strings, in messages, JNI (const char*),
even like: String str = "string"; - that's automatic.
Also operator "+" was overloaded for Strings, but Java prohibits such
overloading! (Consider this: String str = "Hello"+","+"world"+17+true;)
If programmers would be allowed to extend Strings, that probably
would cause a lot of unpredictable behaivor, if everybody would use
separate type of Strings each other.
Plus, Strings are immutable. That means, once created, they can't be
changed, a that's clears understanding and programming.

So, that's a good design.

If you want to add some special functionality in Java's String,
consider following approach:
package com.cranmer.util;
public class StringUtil
{
public static String doSomeTrick(String s) { }
.....
}
and call that like: String my = StringUtil.doSomeTrick("Hi");

Ivan Porty.