盒装原始值的动态比较

Question

我需要对两个原始（数字！）类型（都装箱为对象）进行泛型比较以找到更大的一个。我不能使用泛型，因为我只获取对象，但我知道未装箱的值是原始数字（int、short、long、float 等），所以我可以转换为 IComparable。

我怎样才能比较那些？ CompareTo() 会抛出错误，因为它们是不同的类型，但 ChangeType 会导致 OverflowException...?

        public static int Compare(object value1, object value2)
    {
        //e.g. value1 = (object)(int)1; value2 = (object)(float)2.0f
        if (value1 is IComparable && value2 is IComparable)
        {
            return (value1 as IComparable).CompareTo(value2);
            //throws exception bc value1.GetType() != value2.GetType()
        }
        throw new ArgumentException();
    }

Answer 1

也许是

public static int Compare(object value1, object value2)
{
    if (value1 is double || value2 is double)
    {
        double d1 = Convert.ToDouble(value1);
        double d2 = Convert.ToDouble(value2);
        return d1.CompareTo(d2);
    }

    if (value1 is float || value2 is float)
    {
        float f1 = Convert.ToSingle(value1);
        float f2 = Convert.ToSingle(value2);
        return f1.CompareTo(f2);
    }

    long x1 = Convert.ToInt64(value1);
    long x2 = Convert.ToInt64(value2);
    return x1.CompareTo(x2);
}

byte、short、int类型都可以转为long而不损失精度。

Answer 2

这是另一种方式：

public void test() {

        Object o1 = 5465.0;
        Object o2 = 5465;
        Object o3 = 5465l;
        Object o4 = "5465";

        System.out.println(compare(o1, o2));
        System.out.println(compare(o1, o3));
        System.out.println(compare(o2, o3));
        System.out.println(compare(o3, o4));
}

public Double convertNumber(Object o) {
        if (o instanceof Double) {
            return (Double) o;
        } else if (o instanceof Long) {
            return ((Long) o).doubleValue();
        } else if (o instanceof Integer) {
            return ((Integer) o).doubleValue();
        } else if (o instanceof String) {
            try {
                return Double.parseDouble((String) o);
            } catch (Exception e) {
            }
        }
        return null;
}

public int compare(Object o1, Object o2) {

        if (o1 == null && o2 == null)
            return 0;

        if (o1 == null || o2 == null)
            return -1;

        Double asNumber1 = convertNumber(o1);
        if (asNumber1 == null)
            return String.valueOf(o1).compareTo(String.valueOf(o2));

        Double asNumber2 = convertNumber(o2);
        return asNumber2 == null ? -1 : asNumber1.compareTo(asNumber2);


    }

盒装原始值的动态比较

Dynamic comparison of boxed primitive values

c#

boxing

icomparable

object

primitive-types