Sams Teach Yourself Java™ in 21 Days (Covering Java 8), Seventh Edition

Day 3. Working with Objects

Java is an object-oriented programming language. When you do work in Java, you primarily use objects to get the job done. You create objects, modify them, change their variables, call their methods, and combine them with other objects. You develop classes, create objects out of those classes, and use them with other classes and objects.

Today, you work extensively with objects as you undertake these essential tasks:

Creating objects

Testing and modifying their class and instance variables

Calling an object’s methods ...