README.md

Java Functional Programming

 

Master Java functional features and write more consice and easy to parallel code 💪

 

Why should you care?

⚡️ Nowadays every Java developer uses some functional programming features in an everyday job. So make sure you've checked out the rest of the materials in this module and build strong skills using these language features!

The main idea is to keep Java OO language but enable some functional programming features. It does two things:

• makes the code more concise
• allows easier parallelization

Java SE 8+ provides a rich API that enables functional programming features based on

• Functional Interfaces
• Lambdas
• Stream API
• Optional API

At the end of this module you will be able to

Write this

public List<Account> findAllGmailAccounts(List<Account> accounts) {
        return accounts.stream()
                .filter(a -> a.getEmail().endsWith("@gmail.com"))
                .collect(toList());
}

instead of this

public List<Account> findAllGmailAccounts(List<Account> accounts) {
    List<Account> gmailAccounts = new ArrayList<>();
        for (Account account : accounts) {
            if (account.getEmail().endsWith("@gmail.com")) {
                gmailAccounts.add(account);
            }
        }
    return gmailAccounts;
}

Among other you will be able to

• use Funtional Interfaces and Lambdas in order to pass around functions like first-class citizens ✅
• process data collections in a concise and easy way to understand using Stream API ✅
• write null-safe code using Optional API ✅

Learn or skip ?

Think you're cool enough to skip this topic? 😎 Hand on a sec...☝️ Can you easily understand and write lambdas like this?

runnable -> () -> {
            Thread t = new Thread(runnable);
            t.start();
            return t;
};

or stream pipelines like this ? 🧐

accounts.stream()
        .flatMap(a -> Stream.of(a.getFirstName(), a.getLastName()))
        .map(String::toLowerCase)
        .flatMapToInt(String::chars)
        .mapToObj(c -> (char) c)
        .collect(groupingBy(identity(), counting()));

No worries if you don't! Be patient, do the exercises in this module, and you will be able to do not only this 👆. You will understand and use functional programming techniques far beyond your expectations 🔥