Re: Strings...immutable?
On Mar 19, 5:22 pm, Mark Space <marksp...@sbc.global.net> wrote:
printdude1...@gmail.com wrote:
So where the hell did I get the idea that x would change along with
s? Surely I didn't come up with it on my own?
I couldn't tell ya, but it *is* the general case in Java. Most objects
will behave as you describe. Strings are special, although any object
could have this behavior if it wanted.
Here's maybe where you got the idea, perhaps from a poorly thought-out
example that exhibits the kind of behavior your are describing.
package stringtest;
public class Main
{
public static void main(String[] args)
{
StringBuffer s = new StringBuffer( "hello" );
StringBuffer t = s;
System.out.println( s + " " + t );
t.append( " good-bye");
System.out.println( s + " " + t);
}
}
init:
deps-jar:
compile:
hello hello
hello good-bye hello good-bye
debug:
BUILD SUCCESSFUL (total time: 1 second)
So there's the behavior, but it's from a StringBuffer, not a String.
Big difference there. But the difference between a StringBuffer and a
String might not be really easy for someone new to distinguish.
From
http://home.cogeco.ca/~ve3ll/jatutor7.htm
String class objects are immutable (ie. read only). When a change is
made to a string, a new object is created and the old one is disused.
This causes extraneous garbage collection if string modifier methods
are used too often. The StringBuffer class should be used instead of
String objects in these cases.
Makes all kinds of sense now. Would have saved alot of agony if I had
just done a google search