Book Image

Learn Java with Projects

By : Dr. Seán Kennedy, Maaike van Putten
5 (3)
Book Image

Learn Java with Projects

5 (3)
By: Dr. Seán Kennedy, Maaike van Putten

Overview of this book

Learn Java with Projects stands out in the world of Java guides; while some books skim the surface and others get lost in too much detail, this one finds a nice middle ground. You’ll begin by exploring the fundamentals of Java, from its primitive data types through to loops and arrays. Next, you’ll move on to object-oriented programming (OOP), where you’ll get to grips with key topics such as classes, objects, encapsulation, inheritance, polymorphism, interfaces, and more. The chapters are designed in a way that focuses on topics that really matter in real-life work situations. No extra fluff here, so that you get more time to spend on the basics and form a solid foundation. As you make progress, you’ll learn advanced topics including generics, collections, lambda expressions, streams and concurrency. This book doesn't just talk about theory—it shows you how things work with little projects, which eventually add up to one big project that brings it all together. By the end of this Java book, you’ll have sound practical knowledge of Java and a helpful guide to walk you through the important parts of Java.
Table of Contents (22 chapters)
1
Part 1: Java Fundamentals
9
Part 2: Object-Oriented Programming
15
Part 3: Advanced Topics

The synchronized keyword

As we’ve just seen, working with many threads can bring potential new problems, such as data integrity. The synchronized keyword is a Java keyword that uses a lock mechanism to achieve synchronization. It is used to control access to critical sections of code for different threads. When a thread is inside a synchronized method or block, no other thread can enter any of the synchronized methods for the same object.

To understand the need for synchronization, let’s consider another simple concurrent counting scenario where unexpected outcomes can occur. We have a class named Count with a static counter variable. This class also has a method, incrementCounter, which increments the value of counter by one:

public class Count {    static int counter = 0;
    static void incrementCounter() {
        int current = counter;
       ...