Chapter 2 - Everything Is an Object
The Java language assumes that you want to do only object-oriented programming, so (almost) everything in Java is an object.
You manipulate objects with references You treat everything as an object, using a single consistent syntax. Although you treat everything as an object, the identifier you manipulate is actually a “reference” to an object.
String s; You must create all the objects When you create a reference, you want to connect it with a new object.
Chapter 1 - Introduction to Objects
The progress of abstraction Five basic characteristics of object-oriented programming:
Everything is an object.
A program is a bunch of objects telling each other what to do by sending messages.
Each object has its own memory made up of other objects.
Every object has a type
All objects of a particular type can receive the same messages.
An object has an interface The interface determines what request you can make for a particular object.