How can used replace()?

[Hades Pan]

class Happy3 {
static String s="Hello";
public static void main(String args[]) {
Happy3 h=new Happy3();
System.out.println(methodA(s));
}
public static String methodA(String s) {
s.replace('i','e');
s+=" World !!!" ;
return s;
}
}
It will output "Hello World!!!"
It was no used in above cord on replace.

[Nain Hwu]

Hades,
String object is immutable, i.e. not changable.
Any String method that needs to change the contents
will create a new String and return a reference to the
new String. If there is no change, a reference to the original
String is returned.
Whatever the case is, your code

s.replace('i','e');

simply has no effect on 's'.
[This message has been edited by Nain Hwu (edited December 04, 2001).]

[Hades Pan]

I got it thank you !

[Jane Griscti]

Hi Hades,
Nain is right in saying that s.replace('i','e') has no effect on 's' and is returning a reference to the original string. This is happening because
(1) there is no 'i' in 'Hello'. The definition for String replace is <code>String replace( oldChar, newChar )</code>.
(2) you are not storing the new string reference anywhere
Try the following
<code>
class Happy3 {
static String s ="Hello";

public static void main(String args[]) {
Happy3 h = new Happy3();
System.out.println(methodA(s));
System.out.println( s );
}
public static String methodA(String s) {
String str = s.replace('e','i');
str += " World !!!" ;
return str;
}
}

Output:
Hillo World !!!
Hello

</code>
A new String is created in methodA(), the original String 's' is not changed.
Hope that helps.
------------------
Jane Griscti
Sun Certified Programmer for the Java� 2 Platform
Co-author Mike Meyers' Java 2 Certification Passport

[Hades Pan]

OK I see it Thank Jane Griscti very much~~!