Referencing a Method KNOWN at runtime

Question

I use Callback classes (usually based on function pointers) in every language I write. It makes it really easy to build complex state machines with the minimal possible code and memory usage.
I am really excited about reflection after experimenting with it. It appears that java might be the 3rd language I can apply my design patterns to.
However, my prototype is in-elligant to say the least and I am looking to parameterize it so that I can easily apply the same template across the entire footprint of this project. Here is my crude java callback class:
public class AttribCallback
AttribCallback( Object target, String zMethod ) throws NoSuchMethodException
    int iMethod = 0;
    Class clsTarget = target.getClass();
    java.lang.reflect.Method aMeth[] = getClass().getMethods();
    for( ;iMethod<aMeth.length;iMethod++ )
    { //xx TODO : FIND A BETTER way to do this!
      if( "Call"==aMeth[iMethod].getName() )
           break;
    m_methExec = clsTarget.getMethod(zMethod,aMeth[iMethod].getParameterTypes());
    m_oTarget = target;
  public com.castel.casdk.CASsymbol Call( java.util.Map.Entry<String,String> rEntry )
    try
       Object args[] = { rEntry };
       return (CASsymbol)m_methExec.invoke(m_oTarget,args);
    catch( Throwable rEx )
       Lib.LogErr( "XMLTag.AttribCB::Call() caught UNHANDLED EX=[%s]\n",rEx.toString());
       return CASsymbol.CAS_Status_Failed;
  java.lang.reflect.Method m_methExec;
  Object m_oTarget;
};I have method "CASsymbol Call( java.util.Map.Entry<String,String> rEntry )" clearly defined above in my callback class. Presumably, object target (passed to my constructor) is a user of my callback that has a method with the same sigature. My ctor looks up a known (at compile time) method it has with the same signature and uses its signature to retrieve the target method for later execution (say an asynch event subscribed to by this callback occurs).
The problem (solved crudely in the ctor above), is to get a reference to this Call method in my callback class so that I can use its parameters (and hopefully return type in the future) to retrieve the target method. This target method defined elsewhere can then be "Called Back" using AttribCallback.Call() without knowing anything but its name and the object that defines it. So six target methods can be defined in the Using class (all with the same singature) and targeted as my different callbacks under varying conditions or states.
AttribCallback.Call's signature is known at compile time. I can already reference classes by name (such as com.castel.package.AttribCallback.class). Is there a way for me to reference my method by name? (equivalent to &AttribCallback::Call in C++)
If not (and I am forced to search), is there a more fool-proof way for me to ensure I retrieved the right method than simply using the methods name in my search? What about the methods return type?
Finally, if I were to abstract the whole callback idea to a base class, is there a way for me to build a parameterized base class where the signature of my callback could be passed as a parameter (return type and parameter list)?
I might than define Call in my base class possibly at class initialization time, if possible?
I look forward to any feedback in this regard,
James
Beverly, MA

Answer 1

A crude generic class.
public class AttribCallback<Return, Param> {
     java.lang.reflect.Method m_methExec;
     Object m_oTarget;
     AttribCallback(Object target, String zMethod, Class<Param> classType) throws NoSuchMethodException {
          Class clsTarget = target.getClass();
          m_methExec = clsTarget.getMethod(zMethod, new Class[] { classType });
          m_oTarget = target;
     @SuppressWarnings("unchecked")
     public Return Call(Param rEntry) {
          try {
               Object args[] = { rEntry };
               return (Return) m_methExec.invoke(m_oTarget, args);
          catch (Throwable rEx) {
               return null;
     public static void main(String args[]){
          try {
               AttribCallback<String,String> ac = new AttribCallback<String, String>("ramki","concat",String.class);
               String returned = ac.Call("ramki");
               System.out.println("The return is "+returned);
          catch (NoSuchMethodException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
}