Fixed-length numbers and strings

Question

Hello,
I have to make a critical decision about API usage. I would be grateful if some of you could share their experiences. This will help me make an informed decision and avoid potential trouble further down the line.
I have to use fixed-length integer numbers and fixed-length strings such as for example:
-A string that is exactly 5-letter long (no longer and no shorter than 5 letters). e.g. "abcde"
-A number that is exactly 8-digit long (no longer and no shorter than 8 digits). e.g. "12345678"
Ideally I would get some sort of exception when the "container" for the letters or digits contains less or more than what the spec says.
I am not sure which classes or primitives could meet my needs. As far as the fixed-length string is concerned I initially thought of using a array of chars but an array of chars is not that easy to manipulate and contains "garbage" until you explicitely fill it in with data. I'd rather some sort of class.
Can anyone please advise me?
Thanks in advance,
Julien.

Answer 1

Why not use the same thing like in the case of the String
/**Warning: this is an example and not very good design.*/
public class FixedInteger {
   private int min, max;
   private int value;
   public int getValue() { return value;}
   public void setValue(int v) {
        if (v >= min && v < max) {
            throw new Exception();
        value = v;
   /**ex. min = 10000, max = 100000 for 5 digit numbers*/
   public FixedInteger(int min, int max, int value) {
       this.min = min; this.max = max;
       setValue(value);
}You can do tricks like convert it to immutabla like the String and Integer class in the Java Api
Edited by: szgy on Oct 5, 2007 2:22 PM