Using a string to reference a variable

Question

hi all,
i've encountered an interesting scenario where i need to use a string to reeference the value of a variable...the following would show the scenario in a simpler way...
let's say we have such function called foo:
void foo(String aString)
int a = 20;
int b = 20;
system.out.println(?????);
now let's say i run the function as:
foo("a")
and i want it to return:
20
what should be put to replace those "?????" in my function above?
please note that variables "a" and "b" are arbitary and so having a conditional statement like the following would NOT be useful:
void foo(String aString)
int a = 20;
int b = 20;
if (aString.equals("a"))
system.out.println(a);
if (aString.equals("b"))
system.out.println(b);
thank you very much!

Answer 1

There are two possibilities here.
The preferable one, if you have control over the names and nature of the variables, then don't use individual variables - use a Hashtable (or any implementation of Map). Your code would then look something like:void foo(String aString)
    Map table = new Hashtable();
    table.put("a", new Integer(20));
    table.put("b", new Integer(30));
    system.out.println(table.get(aString));
}The down side to this is that you have to use Integers - Maps can't take primitives.
If, on the other hand, you have to have variables, then take a look at using reflection. It's more complicated than using Maps, and less efficient, so I would recommend the first technique if possible.
RObin