(Java) I can't figure out how to populate an array with a counter controlled loop which is required

I have to: Create an array that models a deck of cards. For example, “1_of_diamonds” represents the ace of diamonds, “2_of_diamonds” represents the 2 of diamonds, up to “13_of_diamonds”, which represents the King of diamonds. The suits clubs, hearts and spades are represented in a similar manner. All these elements should be in a single array. The array should be populated using a counter controlled loop. Output the contents of the array to the screen. Shuffle the deck.

I have the code to shuffle it working but I do not know how to populate the array with a counter controlled loop.

//this is my code

import java.util.Random;


public class Cards{
    public static void main(String[] args){
        Scanner input = new Scanner(System.in);

} //end main

public String[] shuffle(String[] deck) {
    Random rnd = new Random();
    for (int i = deck.length - 1; i >= 0; i--)
    {
        int index = rnd.nextInt(i + 1);
        // Simple swap
        String a = deck[index];
        deck[index] = deck[i];
        deck[i] = a;
    }
    return deck;

}
}// end class