Java Reflection: Create an implementing class

Question

Class someInterface = Class.fromName("some.package.SomeInterface"); 

How do I now create a new class that implements someInterface?

I need to create a new class, and pass it to a function that needs a SomeInterface as an argument.

Answer 1

Easily, java.lang.reflect.Proxy to the rescue!

Full working example:

interface IRobot {      String Name();      String Name(String title);      void Talk();      void Talk(String stuff);      void Talk(int stuff);      void Talk(String stuff, int more_stuff);      void Talk(int stuff, int more_stuff);      void Talk(int stuff, String more_stuff); }  public class ProxyTest {     public static void main(String args[]) {         IRobot robot = (IRobot) java.lang.reflect.Proxy.newProxyInstance(                 IRobot.class.getClassLoader(),                 new java.lang.Class[] { IRobot.class },                 new java.lang.reflect.InvocationHandler() {              @Override             public Object invoke(Object proxy, java.lang.reflect.Method method, Object[] args) throws java.lang.Throwable {                 String method_name = method.getName();                 Class<?>[] classes = method.getParameterTypes();                  if (method_name.equals("Name")) {                     if (args == null) {                         return "Mr IRobot";                     } else {                         return args[0] + " IRobot";                     }                 } else if (method_name.equals("Talk")) {                     switch (classes.length) {                         case 0:                             System.out.println("Hello");                             break;                         case 1:                             if (classes[0] == int.class) {                                 System.out.println("Hi. Int: " + args[0]);                             } else {                                 System.out.println("Hi. String: " + args[0]);                             }                             break;                         case 2:                             if (classes[0] == String.class) {                                 System.out.println("Hi. String: " + args[0] + ". Int: " + args[1]);                             } else {                                 if (classes[1] == String.class) {                                     System.out.println("Hi. int: " + args[0] + ". String: " + args[1]);                                 } else {                                     System.out.println("Hi. int: " + args[0] + ". Int: " + args[1]);                                 }                             }                             break;                     }                 }                 return null;             }         });          System.out.println(robot.Name());         System.out.println(robot.Name("Dr"));         robot.Talk();         robot.Talk("stuff");         robot.Talk(100);         robot.Talk("stuff", 200);         robot.Talk(300, 400);         robot.Talk(500, "stuff");     } }