In Java objects can be type cast. To type cast an object you must specify
the type in round brackets before the objects identifier. For instance
z = (Integer)a;
If the cast is illegal the Java VM will throw a ClassCastException.
The following code will generate a ClassCastException exception:
Object x = new Integer(0); // Object is base class of all objects in Java so Integer can be assigned to it
System.out.println( (String)x ); // Illegal cast. Object that x refers to is an Integer not a String
The instanceof operator can be used to test the type of class that
an object is. As an Example:
Object x = new Integer(10);
if ( x instanceof Object)
System.println("It's an Object !"); // All classes descend from Object
if ( x instanceof Number)
System.println("It's a Number !"); // Number is super class of Integer
if ( x instanceof Integer)
System.println("It's an Integer !"); // It is an Integer.
if ( x instanceof String)
System.println("It's a String !"); // It's not a String so this won't print
Produces the following output:
It's an Object !
It's a Number !
It's an Integer !
