java – 为什么返回null而不是值？

import java.util.Random;


public class TestCard {

    public static String[] possCards = new String[]{"2","3","4","5","6","7","8","9","10","J","Q","K","A"};
    public static String[] possSuits = new String[]{"C","S","H","D"};
    public static Random rand = new Random();
    static String value;

    public static void main(String[] args) {
            System.out.println(getcard());
    }


    public static void card() {
        String card = possCards[rand.nextInt(possCards.length)];
        String suit = possSuits[rand.nextInt(possSuits.length)];

       value = card + suit;
    }
    public static String getcard(){
        return value;
    }


}