Concat two string without 'losing' memory...

Question

Hi,
I am using this code
public class Test{
     Test(){
          String s = "a";
          for (int i = 0 ; i < 23 ; i++)
               s = s.concat(s);
               //s += s;
          System.out.println(s.length() / 1048576);
System.out.println("MAX MEMORY = " + Runtime.getRuntime().maxMemory() / 1048576 + "MB");
System.out.println("TOTAL MEMORY = " + Runtime.getRuntime().totalMemory() / 1048576 + "MB");
System.out.println("FREE MEMORY = " + Runtime.getRuntime().freeMemory() / 1048576 + "MB");
               //s += s;
               s = s.concat(s);
          System.out.println(s.length() / 1048576);
System.out.println("MAX MEMORY = " + Runtime.getRuntime().maxMemory() / 1048576 + "MB");
System.out.println("TOTAL MEMORY = " + Runtime.getRuntime().totalMemory() / 1048576 + "MB");
System.out.println("FREE MEMORY = " + Runtime.getRuntime().freeMemory() / 1048576 + "MB");
     public static void main(String args[]){
          Test t = new Test();
}I get on console this
8
MAX MEMORY = 508MB
TOTAL MEMORY = 508MB
FREE MEMORY = 483MB
16
MAX MEMORY = 508MB
TOTAL MEMORY = 508MB
FREE MEMORY = 451MB
It took 32MB which is very much. Can I do something, and what I should do, to take less memory? It is logical if I had string of size 8 MB and to the same string I add 8 MB, to be FREE MEMORY 8 MB less then before, but not 32 MB.
Thank you.

Answer 1

Don't use the method concat on strings. Use a
StringBuffer or StringBuilder instead. If I instead
String s = "a"; put
StringBuffer s = new StringBuffer();
s.append("a");and instead
s = s.concat(s);put
s.append(s.toString());
FREE MEMORY becomes 472MB and 428MB, before was 483MB and 451MB.
>
Do also note that the GC executes when it needs to,
and the memory that has been allocated for the old
strings can be collected later on.And my aplication breaks :(
>
Kaj