🚀 go-pugleaf

Lewis Chan wrote:

> I just started to learn Java.  I learned that Strings are constant and
> their values cannot be changed after they are created. And that
> StringBuffers support mutable strings and should be used if the string
> needs to be manipulated.
>
> I created the following class which compiles and runs ok.  Therefore, it
> seems like I can manipulate a String.  Pls help me understand this.
> Thanks.
>
> class ChangeString {
>       public static void main(String args[]) {
>              String aStr = "string";
>              aStr = aStr.toUpperCase();
>              System.out.println(aStr);
>        }
> }

aStr is a pointer to "string".  What you've done is reassigned aStr to
"STRING" (another memory location) with the statement: aStr =
aStr.toUpperCase();  The effect of this is that "string" is still hanging
around in memory somewhere and is now eligible for garbage collection.  With
a StringBuffer the same memory location would be affected.