How can we call this method

[Babar Qadri]

I have a method in my class. But I dont want to call it straight. Infact, I am getting the method call from database as a string. The string looks like, "classA.calculate(valueA)".

I get this method call, statement, as string using rs.getString(). Is there any way to execute this statement?

Thanks.

[Edwin Dalorzo]

Have you considered using reflection (java.lang.reflect). There is a class named Method, and it has an invokeMethod.


Look at this example. In this case I suppose you have already loaded the necesary classes, if it is not your case, you will have to load them using, for instance, a java.net.URLClassLoader.

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
 
public class Test{

  public static void main(String args[]){

    Class<Sample> aClass = Sample.class;
    Object instance = null;
    try {
      Constructor aDefaultConst = aClass.getConstructor(new Class[0]);
      if (aDefaultConst!=null){
        instance = aDefaultConst.newInstance(new Object[0]);
        if (instance != null){
          Method theMethod = instance.getClass().getMethod("doSomething",new Class[0]); //get method by means of its string name
          if (theMethod != null){
            theMethod.invoke(instance,new Object[0]); //Method invocation
          }
        }
      }
    } catch (SecurityException e) {
      e.printStackTrace();
    } catch (NoSuchMethodException e) {
      e.printStackTrace();
    } catch (IllegalArgumentException e) {
      e.printStackTrace();
    } catch (InstantiationException e) {
      e.printStackTrace();
    } catch (IllegalAccessException e) {
      e.printStackTrace();
    } catch (InvocationTargetException e) {
      e.printStackTrace();
    }
  }

  public static class Sample{
    public void doSomething(){
      System.out.println("Hello World");
    }
  }
}

[ January 16, 2006: Message edited by: Michael Ernest ]

[Bimal Patel]

Hi,

I think its possible by using "Class" class. What do you think guys?
[ January 16, 2006: Message edited by: Bimal Patel ]

[Jeff Albertson]

You many really *need* to store code in your database, but: hands up, how many forum members have needed to do that? What problem are you trying to solve? Perhaps there's a simpler way to do it.

[Rick O'Shay]

Originally posted by Babar Qadri:
I have a method in my class. But I dont want to call it straight. Infact, I am getting the method call from database as a string. The string looks like, "classA.calculate(valueA)".

I get this method call, statement, as string using rs.getString(). Is there any way to execute this statement?

Thanks.

"Why"? He dared ask.

[Jeff Albertson]

Hands up, anyone?

[Bimal Patel]

Hi All,

Whenever there is a need to bind properties with java bean components, and such binding should be custom based, one needs to use reflection API. I think while you're involved in any of the framework creation, that may need.