— Scott McNealy, Sun Microsystems Chairman, President and ceo

the ultimate superclass: 
Object
ArrayList
(These are just a few of the 
methods in ArrayList...there 
are many more.)
Even if you take advantage of polymorphism, 
you still have to create a class with methods 
that take and return your polymorphic type. 
Without a common superclass for everything 
in Java, there’d be no way for the developers 
of Java to create classes with methods that 
could take your custom types... types they never 
knew about when they wrote the ArrayList class.
So you were making subclasses of class Object 
from the very beginning and you didn’t even 
know it. Every class you write extends Object, 
without your ever having to say it. But you can 
think of it as though a class you write looks like 
this:
public class Dog 
extends Object
{ }
But wait a minute, Dog already extends something, Canine. 
That’s OK. The compiler will make 
Canine extend Object 
instead. Except Canine extends Animal. No problem, then the 
compiler will just make Animal extend Object.
Any class that doesn’t 
explicitly extend another 
class, 
implicitly extends 
Object
.
So, since Dog extends Canine, it doesn’t directly extend Object 
(although it does extend it indirectly), and the same is true 
for Canine, but Animal does directly extend Object.
Removes the
object at the
index param
eter. Returns 
‘true’ if the el
ement was in
the list.
Returns ‘true’
if there’s a m
atch for the o
bject parame
ter.
Returns ‘true’
if the list has
no elements
.
Returns eithe
r the index of
the object pa
rameter, or -1
.
Returns the e
lement at thi
s position in t
he list.
Adds the elem
ent to the list
(returns ‘true
’).