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Learn Java with Projects

Learn Java with Projects

By : Dr. Seán Kennedy, Maaike van Putten
4.9 (51)
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Learn Java with Projects

Learn Java with Projects

4.9 (51)
By: Dr. Seán Kennedy, Maaike van Putten

Overview of this book

Learn Java with Projects bridges the gap between introductory Java guides and verbose, theoretical references. This book is crafted to build a strong foundation in Java programming, starting from the Java environment itself. It goes far beyond a superficial review of the topics; it demonstrates, with practical examples, why these fundamentals are crucial for developing a deep understanding of the language. You'll not only learn about classes and objects but also see how these concepts are used in practical scenarios, enhancing your ability to write clean, efficient code. The engaging projects throughout the book provide real-world applications of complex topics, ensuring you can connect theoretical knowledge with practical skills. What makes this book stand out is the expertise of its authors. Seán, a seasoned university lecturer with over 20 years of experience, brings academic rigor and real-world insights, thanks to his work with a prestigious software company. Maaike, a passionate software developer and award-winning trainer, brings hands-on experience and a love for teaching. By the end of this book, you'll not only understand Java's core concepts and the critical advanced ones, but also gain practical experience through projects that mimic real-life challenges.
Table of Contents (22 chapters)
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1
Part 1: Java Fundamentals
9
Part 2: Object-Oriented Programming
15
Part 3: Advanced Topics

Basic operations on maps

Map is quite different from the other collections. Let’s learn how to perform the basic operations on Map.

Adding elements to a map

There is no add() method for Map. We can add elements to a Map interface using the put() method:

Map<String, Integer> gfNrMap = new HashMap<>();gfNrMap.put("Ross", 12);
gfNrMap.put("Chandler", 8);

This adds two key-value pairs to Map. Let’s see how we can get the values out again.

Getting elements from a map

We can get elements from a Map interface using the get() method. This is how we can get the Integer value associated with the Ross key:

int rossNrOfGfs = gfNrMap.get("Ross");

We can also use the key to modify the values of the map.

Changing the elements of a map

We can change the elements in a Map interface using the put() method with an existing key:

gfNrMap.put("Chandler", 9);

The preceding code changes the value of 8 to 9...

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