Generate alphannumeric string in formatted sequence

Please how do I generate a string of random numbers in Java in this formatted order. The string is 5 characters in length (as specified in the format below)

string-string-integer-integer-integer

Every single one of the characters is to be random but in the format specified above. Please help. Thanks.

This is code I am currently having issues with. Please how do I improve it. Thanks.

import java.util.Random;
public class HelloWorld{

     public static void main(String []args){
         Random r = new Random();

         String[] alphabet = {"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"};
         int[]    number = {1,2,3,4,5,6,7,8,9,0};
         for (int i = 0; i < 5; i++) {
             System.out.printf("%s,%s,%d,%d,%d\n", 
               alphabet[i].charAt(r.nextInt(alphabet.length())), 
               number[i].charAt(r.nextInt(number.length())) );
         } // prints 50 random characters from alphabet
     }
}