java - 为什么Calendar类的before,after方法的参数是Object类型的？

Question

源码如下，当参数不是Calendar的实例时返回的是false，但请问这样的比较有意义吗？
我个人觉得参数类型是不是不妥？比如我拿Date类型去做比较，不抱任何错，但其实永远返回的都是false。

public boolean before(Object when) {
    return when instanceof Calendar
        && compareTo((Calendar)when) < 0;
}

public boolean after(Object when) {
    return when instanceof Calendar
        && compareTo((Calendar)when) > 0;
}

//我认为这样比较合理
public boolean after(Canlendar when) {
    return compareTo(when) > 0;
}

Answer 1

So in comparisonCalendar直接用ComparaTo()就好啦

Date和Calendar it is generally accepted as bad.
Same question stackoverflow

I think there is no particular reason for that. java.util.Calendar has some design issues we have to live with, unfortunately.

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Added:
Java8 implements the new package java.time, which is immutable and thread-safe. The main classes and formats in the package

correspond to the old API