Java 数字 字符串 简单操作

数字类型验证：不是数字 或 是负数 返回 true

public static boolean isNotNumOrNegative(Number num) {
    if (num == null) {
        return true;
    }
    if (num instanceof Integer) {
        int v = num.intValue();
        return v < 0;
    }
    if (num instanceof Long) {
        long v = num.longValue();
        return v < 0;
    }
    if (num instanceof BigInteger) {
        BigInteger v = (BigInteger) num;
        return v.compareTo(BigInteger.valueOf(0L)) < 0;
    }
    if (num instanceof BigDecimal) {
        BigDecimal v = (BigDecimal) num;
        return v.compareTo(BigDecimal.valueOf(0L)) < 0;
    }
    return false;
}

public static boolean isNotNumOrNegative(Number... nums) {
    for (Number num : nums) {
        if (isNotNumOrNegative(num)) {
            return true;
        }
    }
    return false;
}

字符串验证：

public static boolean isNullOrEmpty(String val) {
    return val == null || "".equals(val.trim());
}

public static boolean isNullOrEmpty(String... vals) {
    for (String val : vals) {
        if (isNullOrEmpty(val)) {
            return true;
        }
    }
    return false;
}

生成6位随机字符：

public static String getRandomChar() {
    StringBuilder chars = new StringBuilder();
    for (int i = 0; i < 6; i++) {
        int index = new Random().nextInt(26) + 65;
        chars.append((char) index);
    }
    return chars.toString();
}

生成6位验证码：

String.format("%06d", (int) (Math.random() * 1000000))