casting - Explanation of ClassCastException in Java

Question

I read some articles written on "ClassCastException", but I couldn't get a good idea on what it means. What is a ClassCastException?

Answer 1

Straight from the API Specifications for the ClassCastException:

Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance.

So, for example, when one tries to cast an Integer to a String, String is not an subclass of Integer, so a ClassCastException will be thrown.

Object i = Integer.valueOf(42);
String s = (String)i;            // ClassCastException thrown here.