— Scott McNealy, Sun Microsystems Chairman, President and ceo

% java TestObject
class Cat
Cat c = new Cat();
System.out.println(c.hashCode());
hashCode()
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% java TestObject
8202111
Cat c = new Cat();
System.out.println(c.toString());
toString()
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% java TestObject
Cat@7d277f
Prints out a hashcode 
for the object (for 
now, think of it as a 
unique ID).
Tells you if two objects are 
considered ‘equal’ (we’ll talk 
about what ‘equal’ really 
means in appendix B).
Gives you back the 
class that object was 
instantiated from.
Prints out a String message 
with the name of the class 
and some other number we 
rarely care about.
YourClassHere
Every class you write inherits all the 
methods of class Object. The classes 
you’ve written inherited methods you 
didn’t even know you had.

---

210
 
chapter 8
there are no
Dumb Questions
Q: 
Is class Object abstract? 
A:
No. Well, not in the formal 
Java sense anyway. Object is a 
non-abstract class because it’s 
got method implementation 
code that all classes can inherit 
and use out-of-the-box, without 
having to override the methods.
Q: 
Then can you override 
the methods in Object? 
A:
Some of them. But some of 
them are marked 
final
, which 
means you can’t override them.
You’re encouraged (strongly) to 
override hashCode(), equals(), 
and toString() in your own 
classes, and you’ll learn how to 
do that a little later in the book. 
But some of the methods, like 
getClass(), do things that must 
work in a specific, guaranteed 
way. 
Q: