// File: TestClass.java (Module 8)
//
// Author: Rahul Simha
// Created: October 7, 1998
//
// Illustrates the Class class.

import java.lang.reflect.*;

class Obj_A {

  // Data.
  int n;
  double x;

  // Constructors.
  public Obj_A (int n, double x)
  {
    this.n = n;  this.x = x;
  }

  public Obj_A ()
  {
    this (0, 0);
  }

  // Methods.
  public static void print ()
  {
    System.out.println ("Obj_A");
  }

  public String toString ()
  {
    return "Obj_A: n=" + n + ", x=" + x;
  }
}


public class TestClass {

  public static void call_toString (String obj_name)
  {
    try {
      // Get the Class instance first.
      Class c = Class.forName (obj_name);

      // Get a list of methods.
      Method[] method = c.getMethods();

      // Go through and look for toString()
      for (int i=0; i < method.length; i++) {

        // Get name of i-th method.
	String name = method[i].getName();

        // If it is toString ...
        if (name.equals ("toString")) {
	  System.out.println (obj_name + " has a toString() method");
	  try {
            // Create an instance of the object on the fly.
	    Object instance = c.newInstance ();

            // No parameters, so a size=0 array is passed.
            Object[] obj_array = new Object[0];

            // Call the powerful invoke() method.
            // Note: toString returns a string.
	    String output = (String) method[i].invoke (instance, obj_array);

            // Print out the string returned from toString()
	    System.out.println ("String returned: " + output);
	  }
          // Catch a whole bunch of exceptions.
          catch (InstantiationException e) {
            System.out.println (e);
	  }
	  catch (IllegalAccessException e) {
            System.out.println (e);
	  }
	  catch (InvocationTargetException e) {
            System.out.println (e);
	  }
        }
      }
    }
    catch (ClassNotFoundException e) {
      System.out.println (e);
    }
  }

  public static void main (String[] argv)
  {
    // Simple test of Class:
    String s = "hello";
    Class c = s.getClass ();
    System.out.println (c);

    // Use Obj_A instead.
    Obj_A a = new Obj_A ();
    c = a.getClass ();
    System.out.println (c);    

    // Get constructors of Obj_A.
    Constructor[] ctor = c.getConstructors ();
    System.out.println ("Obj_A has " + ctor.length + " constructors");

    // Get methods of Obj_A.
    Method[] method = c.getMethods();
    System.out.println ("Obj_A has " + method.length + " methods: ");
    for (int i=0; i < method.length; i++) {
      String name = method[i].getName();
      System.out.println ("  " + name);
    }

    // Actually call a method (toString) in the object
    call_toString ("Obj_A");
  }
}