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


To be able to create an object of a class, we need a constructor. A constructor is called when you want to create an object of a class. When we create a class without a constructor, Java creates an empty default constructor for us that takes no parameters. If a class is created without a constructor, we can still instantiate it with the default constructor. A good example of this is the Person class that we used previously. When we wanted a new object of the Person class, we wrote the following:

Person me = new Person();

The default constructor is Person(), and it returns a new instance of the Person class. We then assign this returned instance to our variable, me.

A constructor is just like any other method, except for a few differences:

  • A constructor has the same name as the class

  • A constructor can be public or private

  • A constructor doesn't return anything, even void

Let's look at an example. Let's create a simple constructor for our Person class:

public class Person {