二进制的骚操作，省字段，省带宽，提效率...

public enum EXTEND_FLAG_ENUM {

    OVER_WEIGHT(1, "超重"),
    OVER_CUBAGE(1 << 1, "超方"),
    LATE(1 << 2, "晚点"),
    SLOW(1 << 3, "缓行");

    public int value;
    public String name;

    EXTEND_FLAG_ENUM(int value, String name) {
        this.value = value;
        this.name = name;
    }

    public static int addFlag(int org, EXTEND_FLAG_ENUM newFlag){
        return org | newFlag.value;
    }

    public static int removeFlag(int org, EXTEND_FLAG_ENUM oldFlag){
        return org & (~oldFlag.value);
    }
    public static boolean hasFlag(int org, EXTEND_FLAG_ENUM oldFlag){
        return (org & oldFlag.value) > 0;
    }
}
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@Test
public void showTest(){
    // 订单的异常标签初始为0
    int extendFlag = 0;
    // 标记订单超重
    extendFlag = EXTEND_FLAG_ENUM.addFlag(0, EXTEND_FLAG_ENUM.OVER_WEIGHT);
    assertTrue(EXTEND_FLAG_ENUM.hasFlag(extendFlag, EXTEND_FLAG_ENUM.OVER_WEIGHT));
    // 标记订单超方
    extendFlag = EXTEND_FLAG_ENUM.addFlag(extendFlag, EXTEND_FLAG_ENUM.OVER_CUBAGE);
    // 订单确实超重和超方了
    assertTrue(EXTEND_FLAG_ENUM.hasFlag(extendFlag, EXTEND_FLAG_ENUM.OVER_WEIGHT));
    assertTrue(EXTEND_FLAG_ENUM.hasFlag(extendFlag, EXTEND_FLAG_ENUM.OVER_CUBAGE));
}
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@Test
public void showTest2(){
    // [1]
    System.out.println(getExtendFlag(1));
    // [1, 2, 8]
    System.out.println(getExtendFlag(11));
    // [1, 2, 4, 8]
    System.out.println(getExtendFlag(15));
}

public List<Integer> getExtendFlag(int num){
    List<Integer> numList = new ArrayList<>();
    int temp = 1;
    while (temp < 16) {
        if ((num & temp) >= 1) {
            numList.add(temp);
        }
        temp = temp << 1;
    }
    return numList;
}
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bool isPowerOfTwo(int n){
    if (n <= 0) return false;
    return (n & (n - 1)) == 0;
}
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