// polymorphism/Reflect.java

// (c)2021 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://OnJava8.com for more book information.

// {ThrowsException}

class Useful {

public void f() {

}

public void g() {

}

}

class MoreUseful extends Useful {

@Override

public void f() {

}

@Override

public void g() {

}

public void u() {

}

public void v() {

}

public void w() {

}

}

public class Reflect {

public static void main(String[] args) {

Useful[] x = {

new Useful(),

new MoreUseful()

};

x[0].f();

x[1].g();

// Compile time: method not found in Useful:

//- x[1].u();

((MoreUseful) x[1]).u(); // Downcast/Reflect

((MoreUseful) x[0]).u(); // Exception thrown

}

}

/* Output:

___[ Error Output ]___

Exception in thread "main"

java.lang.ClassCastException: Useful cannot be cast to

MoreUseful

at Reflect.main(Reflect.java:28)

*/