Help with returning

[Da1dmoney]

public class Mapper implements ScramblerIF
{
private static String map = "drsjckpwrypwsftylmzxopqtdo";
String str = "null";
char[] chars = str.toCharArray();

int length = str.length();
{
for(int i=0; i<length; i++)
{
char aChar = str.charAt(i);
char upper = Character.toUpperCase(aChar);
int num = (upper - 'A');


char mChar = map.charAt(num);
String chars = Character.toString(mChar);
System.out.print(mChar);	
}
}
public String scramble(String str)
 {
	/*
char[] chars = str.toCharArray();
int length = str.length();
{
for(int i=0; i<length; i++)
{
char aChar = str.charAt(i);
char upper = Character.toUpperCase(aChar);
int num = (upper - 'A');

char mChar = map.charAt(num);
String mapped = Character.toString(mChar);
System.out.print(mChar);	
}*/

return str;
}
}

My program code is finished I am just trying to get the results that are printed put in

System.out.print(mChar);

to be able to be put in the return statement so i can return it. Alot is omitted out int the String Scrambler method because it the same coding as the top. I was messing around with both to try to get it in the return statement.
Any help would be appreciated thanks in advance

[Eranga]

Are you sure that you can compile this code?

[Da1dmoney]

yes i am sure. I can both compile and run it.

[Eranga]

So what's wrong with your return statement in scramble() method?