Book Image

Java Fundamentals

By : Gazihan Alankus, Rogério Theodoro de Brito, Basheer Ahamed Fazal, Vinicius Isola, Miles Obare
Book Image

Java Fundamentals

By: Gazihan Alankus, Rogério Theodoro de Brito, Basheer Ahamed Fazal, Vinicius Isola, Miles Obare

Overview of this book

Since its inception, Java has stormed the programming world. Its features and functionalities provide developers with the tools needed to write robust cross-platform applications. Java Fundamentals introduces you to these tools and functionalities that will enable you to create Java programs. The book begins with an introduction to the language, its philosophy, and evolution over time, until the latest release. You'll learn how the javac/java tools work and what Java packages are - the way a Java program is usually organized. Once you are comfortable with this, you'll be introduced to advanced concepts of the language, such as control flow keywords. You'll explore object-oriented programming and the part it plays in making Java what it is. In the concluding chapters, you'll get to grips with classes, typecasting, and interfaces, and understand the use of data structures, arrays, strings, handling exceptions, and creating generics. By the end of this book, you will have learned to write programs, automate tasks, and follow advanced courses on algorithms and data structures or explore more advanced Java courses.
Table of Contents (12 chapters)
Java Fundamentals

The Object Class

Java provides a special class called Object, from which all classes implicitly inherit. You don't have to manually inherit from this class because the compiler does that for you. Object is the superclass of all classes:

Figure 5.4: Superclass Object

This means that any class in Java can be upcast to Object:

Object object = (Object)person;
Object object1 = (Object)student;

Likewise, you can downcast to the original class:

Person newPerson = (Person)object;
Student newStudent  = (Student)object1;

You can use this Object class when you want to pass around objects whose type you don't know. It's also used when the JVM wants to perform garbage collection.