why does this code show an error

[ishween2k]

class A {
 public void process() { System.out.print(”A,”); } }
class B extends A {
 public void process() throws IOException {
 super.process();
 System.out.print(”B,”);
 throw new IOException();
 } }
class C{
 public static void main(String[] args) {
 try { new B().process(); }
 catch (IOException e) { System.out.println(”Exception”); } }
}

[Markus]

It'd be much more helpful of you to give the error text.

[JosAH]

class A {

 public void process() { System.out.print(”A,”); } }
class B extends A {
 public void process() throws IOException {
 super.process();
 System.out.print(”B,”);
 throw new IOException();
 } }
class C{
 public static void main(String[] args) {
 try { new B().process(); }
 catch (IOException e) { System.out.println(”Exception”); } }
}

Those double quotes are incorrect; you probably used Microsoft Word or something to type that in, don't do that. A second error is your widening of the throws clause for method 'process' in class B. Look up the Liskov Substitution principle and you'll see.

kind regards,

Jos (ex-moderator)