Java问题，如何从未知对象获取方法的值 [英] Java Question, how to get the value of a method from an unknown object

问题描述

我在系统中定义了很多对象，也许有1000个对象， 其中一些具有这种方法:

I have lots of object defined in the system, perhaps 1000 objects, and some of them have this method:

public Date getDate();

无论如何，我可以执行以下操作:

Is there anyway I can do something like this:

Object o = getFromSomeWhere.....;

Method m = o.getMethod("getDate");
Date date = (Date) m.getValue();

推荐答案

如果可以使它们全部实现接口，那肯定是最好的选择.但是，反射也将起作用，并且您的代码几乎在那里:

If you can make them all implement an interface, that would certainly be the best option. However, reflection will also work, and your code was nearly there:

Object o = getFromSomeWhere.....;
Method m = o.getClass().getMethod("getDate");
Date date = (Date) m.invoke(o);

(坦白地说，您需要处理很多异常)

(There's a bunch of exceptions you'll need to handle, admittedly...)

举一个完整的例子:

import java.lang.reflect.*;
import java.util.*;

public class Test
{
    public static void main(String[] args) throws Exception
    {
        Object o = new Test();
        Method m = o.getClass().getMethod("getDate");
        Date date = (Date) m.invoke(o);
        System.out.println(date);
    }

    public Date getDate()
    {
        return new Date();
    }
}

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