Re: Dynamic method calls

Lew <>
Thu, 21 Dec 2006 12:02:23 -0500
Denis Palas wrote:

Dear All

I am trying to use dynamic method calls, and have written the below code,
but not getting any results. Could you please help to point out my mistakes?

Thank you in advance

// ------------------------------------- My code -------------------------

First, fix any compilation errors.

import java.lang.reflect.*;

Assiduously avoid use of reflection.

import java.text.*;
import java.util.*;

public class TestClass {

public static void main(String[] args) throws Exception {

You should indent code (using spaces, not TABs) that you post, to enhance


Object myres=0 ;

This only works in Java 5 +. You might have made the intent clearer by
declaring the variable as Integer.

Why the throwaway initialization anyway?

String Functionstest[][]= {

Java programming convention is that variable and method names begin with a
lower-case letter, and that each subsequent "word" component begin with an
upper-case letter: "functionsTest'.



for (int j = 0; j < Functionstest[0].length - 1; j++) {
   parameterTypes[j] = Integer.TYPE;

So "Mult1" is a parameter of Integer.TYPE.

   parameters[j] = new Integer(Functionstest[0][j+1]);

Method m = c.getMethod(Functionstest[0][0], parameterTypes);

You've already declared "Functionstest[0][0]" to be an Integer.TYPE parameter,
despite that its value does not parse to an integer. It should not also be a
method name.

myres = m.invoke(this, parameters);


} // End Try

catch (IllegalAccessException e) { }
  catch (InvocationTargetException e) { }
  catch (NoSuchMethodException e) { }

You should not ignore Exceptions. The error messages probably would have led
you to a solution by now.

System.out.println("The result is = " + myres);


If this is an exercise to learn reflection, it's useful. Otherwise there are
better ways to accomplish the task.

- Lew

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