Java: Random card generator without arrays

I'm learning Java and got stuck on one of the "Loops" lesson exercises. Wherever I look online, this kind of question is solved using arrays; while I'm aware this is probably the more efficient way, it bugs me that I can't understand what is wrong with my solution. What would be a good solution here?

package practice05;

import java.util.Random;

public class Practice04
{
public static void main(String[] args)
{
    new Practice04();
}
public Practice04()
{
    String number = "";
    String suit = "";
    System.out.println(number(number) + " " + sign(suit));
}

private String number(String number)
{
    Random n = new Random();
    int num = n.nextInt(14);
    if (num > 10 || num < 2)
    {
        switch (num)
        {
            case 1: number = "Ace";
            case 11: number = "Ace";
            case 12: number = "Jack";
            case 13: number = "Queen";
            case 14: number = "King";
        }
    }
    else
    {
        number = Integer.toString(num);
    }
    return number;
}

private String sign(String suit)
{
    Random s = new Random();
    int sign = s.nextInt(4);
    switch (sign)
    {
        case 1: suit = "of clubs";
        case 2: suit = "of diamonds";
        case 3: suit = "of hearts";
        case 4: suit = "of spades";
    }
    return suit;
}
}