Book Image

The Java Workshop

By : David Cuartielles, Andreas Göransson, Eric Foster-Johnson
4 (2)
Book Image

The Java Workshop

4 (2)
By: David Cuartielles, Andreas Göransson, Eric Foster-Johnson

Overview of this book

Java is a versatile, popular programming language used across a wide range of industries. Learning how to write effective Java code can take your career to the next level, and The Java Workshop will help you do just that. This book is designed to take the pain out of Java coding and teach you everything you need to know to be productive in building real-world software. The Workshop starts by showing you how to use classes, methods, and the built-in Collections API to manipulate data structures effortlessly. You’ll dive right into learning about object-oriented programming by creating classes and interfaces and making use of inheritance and polymorphism. After learning how to handle exceptions, you’ll study the modules, packages, and libraries that help you organize your code. As you progress, you’ll discover how to connect to external databases and web servers, work with regular expressions, and write unit tests to validate your code. You’ll also be introduced to functional programming and see how to implement it using lambda functions. By the end of this Workshop, you’ll be well-versed with key Java concepts and have the knowledge and confidence to tackle your own ambitious projects with Java.
Table of Contents (20 chapters)

Sorting Collections

As we have seen, there are some classes in the collections framework that force the items within them to be sorted. Examples of that are TreeSet and TreeMap. The aspect to explore in this section is how to use existing sorting mechanisms for lists, but also for cases that have datasets with more than one value per data point.

The exercise we are doing throughout this chapter is a good example of a case where there are data points with more than one value. For each data point, we need to store the word for which we are calculating the frequency and the frequency itself. You might think that a good technique to sort that out is by storing the information in the form of maps. The unique words could be the keys, while the frequencies could be the values. This could be achieved by modifying the final part of the previous program to look like this:

Map map = new HashMap();
while (iterator.hasNext()) {
    //  point to next element
...