/*
 * DoNothing.java
 *
 */

import java.lang.reflect.*;
import java.util.Arrays;

/**
 * Creates a dynamic proxy that simply does nothing and returns null
 * or "0", when any of its methods are called.
 */
public class DoNothing implements InvocationHandler {
    
    /**
     * Creates a do-nothing proxy that implements all the interfaces.
     */
    public static Object newInstance(Class[] interfaces) {
        return Proxy.newProxyInstance(DoNothing.class.getClassLoader(), interfaces, new DoNothing());
    }
    
    /**
     * Creates a do-nothing proxy that implements one interface.
     */
    public static Object newInstance(Class iface ) {
        return newInstance( new Class[]{iface});
    }


    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Class returnType = method.getReturnType();
        
        // if the method isn't supposed to return anything,
        // return null
        if(returnType == void.class) {
            return null;
        }
        
        // if we have a return value, return whatever it is
        // that new arrays of our return type are filled with.
        // this is a convenient way to get "0" as the right
        // kind of primitive, or null for objects, in one
        // line of code.
        return Array.get( Array.newInstance(returnType,1), 0);
    }
    
    
}