計算hashCode通用計算公式

1.java計算公式

@Override
    public int hashCode() {
        //設置初始值
        int result = 17;

        //假設有效域為: name,age,idCardNo,incomeAnnual,sex,brithDay
        int c = 0;
        //計算name (String為對象類型,他的計算直接調用本身的hashCode)
        c = name.hashCode();
        result = result * 37 + c;

        //計算age (int/byte/char/short類型,他的計算直接調用本身的值)
        c = this.getAge();
        result = result * 37 + c;

        //計算idCardNo (long類型,他的計算 (int)(field^(field >>> 32)) 無符號右移32位)
        c = (int) (this.idCardNo ^ (this.idCardNo >>> 32));
        result = result * 37 + c;

        //計算 incomeAnnual (double類型,他的計算 Double.doubleToLongBits(field)后,再按Long類型計算 )
        //(float類型,他的計算 Float.floatToIntBits(field)  )
        long tmp = Double.doubleToLongBits(this.incomeAnnual);
        c = (int) (tmp ^ (tmp >>> 32));
        result = result * 37 + c;

        //計算 sex (sex為boolean類型,他的計算直接調用 c=sex?1:0)
        c = this.isSex() ? 1 : 0;
        result = result * 37 + c;

        //計算 brithDay (brithDay為Date對象類型,他的計算直接調用 本身的hashCode)
        c = this.getBirthDay().hashCode();
        result = result * 37 + c;

        return result;
    }

 2. .net計算公式

public class HashCodeTest
    {
        public static void Excute()
        {
            var man = new Man()
            {
                Age = 10,
                BirthDay = new DateTime(1950,1,1),
                IdCardNo = 2139095040,
                IncomeAnnual = 10000000.5,
                Name = "Aven",
                Sex = true
            };
            var hasCode = man.GetHashCode();
            Console.WriteLine(hasCode);
        }
    }

    class Man
    {
        public long IdCardNo { get; set; }
        public int Age { get; set; }
        public string Name { get; set; }
        public double IncomeAnnual { get; set; }
        public bool Sex { get; set; }
        public DateTime BirthDay { get; set; }

        public override int GetHashCode()
        {
            //設置初始值
            int result = 17;

            //假設有效域為: name,age,idCardNo,incomeAnnual,sex,brithDay
            int c = 0;
            //計算name (String為對象類型,他的計算直接調用本身的hashCode)
            c = Name.GetHashCode();
            result = result * 37 + c;

            //計算age (int/byte/char/short類型,他的計算直接調用本身的值)
            c = this.Age;
            result = result * 37 + c;

            //計算idCardNo (long類型,他的計算 (int)(field^(field >> 32)) 有符號右移32位,符號位不移動)
            c = (int)(this.IdCardNo ^ (this.IdCardNo >> 32));
            result = result * 37 + c;

            //計算 incomeAnnual (double類型,他的計算 BitConverter.DoubleToInt64Bits(field)后,再按Long類型計算 )
            //(float類型,他的計算 BitConverter.ToInt32(BitConverter.GetBytes(this.IncomeAnnual),0) )
            long tmp = BitConverter.DoubleToInt64Bits(this.IncomeAnnual);
            c = (int)(tmp ^ (tmp >> 32));
            result = result * 37 + c;

            //計算 sex (sex為boolean類型,他的計算直接調用 c=sex?1:0)
            c = this.Sex ? 1 : 0;
            result = result * 37 + c;

            //計算 brithDay (brithDay為Date對象類型,他的計算直接調用 本身的hashCode)
            c = this.BirthDay.GetHashCode();
            result = result * 37 + c;

            return result;
        }
    }