吸血鬼数字是指位数为偶数的数字，可以由一对数字相乘而得到，而这对数字各包含乘积的一半位数的数字，其中从最初的数字中选择的数字可以任意排序。以两个0结尾的数字是不允许的，例如，下列数字都是“吸血鬼”数字： 1260=21*60 1827=21*87 2187=27*81 写一个程序，找出4位数的所有吸血鬼数字Java代码

以下是一个Java程序，可以找出所有4位数的吸血鬼数字：

public class VampireNumbers {
    public static void main(String[] args) {
        for (int i = 1000; i < 10000; i++) {
            int a = i / 1000;
            int b = (i / 100) % 10;
            int c = (i / 10) % 10;
            int d = i % 10;
            if (checkVampireNumber(a, b, c, d, a, b, c, d)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, a, b, d, c)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, a, c, b, d)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, a, c, d, b)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, a, d, b, c)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, a, d, c, b)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, b, a, c, d)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, b, a, d, c)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, b, c, a, d)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, b, c, d, a)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, b, d, a, c)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, b, d, c, a)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, c, a, b, d)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, c, a, d, b)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, c, b, a, d)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, c, b, d, a)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, c, d, a, b)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, c, d, b, a)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, d, a, b, c)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, d, a, c, b)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, d, b, a, c)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, d, b, c, a)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, d, c, a, b)) {
                System.out.println(i);
            }
            if (checkVampireNumber(a, b, c, d, d, c, b, a)) {
                System.out.println(i);
            }
        }
    }

    public static boolean checkVampireNumber(int a, int b, int c, int d, int w, int x, int y, int z) {
        int num1 = 10 * a + b;
        int num2 = 10 * c + d;
        int product = num1 * num2;
        int firstHalf = 10 * w + x;
        int secondHalf = 10 * y + z;
        return product == firstHalf * secondHalf && product % 100 != 0;
    }
}

该程序通过枚举所有可能的数字组合，并检查它们是否满足吸血鬼数字的定义来找出所有4位数的吸血鬼数字。