Question

A while ago I had a similar question when using Class.getMethod and autoboxing, and it made sense to implement this in your own lookup algorithm. But what really confused me a little was that the following is not working either:

public class TestClass
{
    public String doSomething(Serializable s)
    {
        return s.toString();
    }

    public static void main(String[] args) throws SecurityException, NoSuchMethodException
    {
        TestClass tc = new TestClass();
        Method m = tc.getClass().getMethod("doSomething", String.class);
    }
}

String.class implements the Serializable interface and I really expected it to be included in the lookup method. Do I have to consider this in my own lookup algorithms as well?

EDIT: I did read the Javadoc, so let me emphasise the second part of the question: And if so do you have suggestions on how to do that fast (I already had to add some custom matching and converting algorithms and I don’t want it to get too slow)?

Answer 1

As per your edit, you can make use of Class#isAssignableFrom(). Here’s a basic kickoff example (leaving obvious (runtime) exception handling aside):

package com.stackoverflow.q2169497;

import java.io.Serializable;
import java.lang.reflect.Method;

public class Test {

    public String doSomething(Serializable serializable) {
        return serializable.toString();
    }

    public static void main(String[] args) throws Exception {
        Test test = new Test();
        for (Method method : test.getClass().getMethods()) {
            if ("doSomething".equals(method.getName())) {
                if (method.getParameterTypes()[0].isAssignableFrom(String.class)) {
                    System.out.println(method.invoke(test, "foo"));
                }
            }
        }
    }

}

This should print foo to stdout.