为什么字节参数不被识别为整数？

Question

我有以下枚举:

public enum Months {
    JAN(31),
    FEB(28),
    MAR(31),
    APR(30),
    MAY(31),
    JUN(30),
    JUL(31),
    AUG(31),
    SEP(30),
    OCT(31),
    NOV(30),
    DEC(31);

    private final byte DAYS; //days in the month

    private Months(byte numberOfDays){
        this.DAYS = numberOfDays;
    }//end constructor

    public byte getDays(){
        return this.Days;
    }//end method getDays
}//end enum Months

它给了我一个错误,说"构造函数Months(int)是未定义的",虽然我传递了一个有效的字节参数.我究竟做错了什么？

Answer 1

最简单的解决方案是接受一个int值

private Months(int numberOfDays){
    this.DAYS = (byte) numberOfDays;
}

BTW非静态字段应该camelCase不在UPPER_CASE

FEB在某些年份也有29天.

public static boolean isLeapYear(int year) {
    // assume Gregorian calendar for all time
    return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}

public int getDays(int year) {
    return days + (this == FEB && isLeapYear(year) ? 1 : 0);
} 

Answer 2

这些数字是int文字.你必须把它们投射到byte:

 JAN((byte)31),