GENERATION OF NUMBERS

Question

Pls, I have written a program. However, I'm expected to include sub-program that will generate numbers automically for students. For example, the number for first student may be 12367GE and the next may 56789AW.
Pls, how do I do that?
Thanks

Answer 1

Thare is no problem in generating random number you can use Random class for that.
But the problem is making sure that your applet generate unique numbers.
No Random Number generation algorithm garantees the generation of unique number they just geive "Random Numbers" and there can be duplicates.
So your program will need a way to store the previously generatly numbers so when you generate the next one you have to compare the generated number with the old ones to make sure it is unique if not uniques you have to repeat the proces until you get a unique number.
Using a file is not good idear since once the file grow in to a large one the algorithm will run very slow.
Keeping them in memory is not that good becouse you will loose them when the server is restarted and also can caoue out of memory errors.
A simple database will be the best option to keep the old data
Ex:-
   while(true){
     int newNumber = generateRandomNumber();
     if (oldNumbers.isUnique(newNumber)){
        oldNumbers.store(newNumber);
        return newNumber;
   }Or you will have to write a random munber algorithm which always garantees to generate unique numbers without actually storing and compairing with the old numbers