Author: Rafael del Nero

Rafael del Nero

Java Champion, a passionate and creative developer who possesses strong technical knowledge and delivers solid systems focused on Spring and Java EE specifications for cloud applications. More than 10 years' experience developing successful, revenue-increasing systems.

  • Streams Set Distinct Java Code Quiz

    Using Streams and Set Collection Factory methods with Java makes code easier to read and maintain.

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  • Exception Chaos Java Code Quiz

    Working correctly with exceptions is crucial to a high-quality application that users enjoy using.

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  • Arrays and Object Reference Java Challenge Code Quiz

    Arrays are objects in Java. Variables in Java actually store references to the object, instead of the real object.

    When we pass an object reference to a method, we are changing the object that is in the heap of the memory.

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  • Parallel Streams Java Code Quiz

    Using streams concurrently with the parallel method is a good idea to optimize performance. However, it’s not always the case that we can use the parallel method, for example, when we depend on the order of logic execution.

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  • Daemon Thread Java Code Quiz

    When we are working with Threads, it’s important to know when to use a daemon or a non-daemon Thread.

    Do you know if the main Thread is a daemon or not? And do you know what a daemon Thread is?

    That’s what you will find out by trying out the following Java Challenge!

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  • Function Calculation Java Challenge

    Functional programming is a very powerful paradigm that makes code more concise and easier to understand.

    In Java, the “Function” functional interface can be used as a first-class citizen function, meaning that we can pass a function to a method and declare it as a variable, giving the developer a lot of power.

    And now it’s time for you now to test your abilities with lambdas and functional interfaces!

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  • Stream Limit Filter Java Challenge

    To manipulate data from a collection by using a Java stream is handy and cleaner than the alternatives.

    When you learn how to use streams, your Java code will be much better, and knowing how to limit and filter data with streams is crucial for you to do something useful with streams in Java.

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  • Neo Stream Search Java Challenge

    Understanding the mechanics of the functional interface Predicate of a Stream is crucial if you want to create something meaningful with streams.

    In this challenge, we will explore important key methods when we work with a stream so that it becomes clear for you what they do.

    Without further ado, let’s go to the Java Challenge!

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  • Jedi Lambda Join Java Challenge

    There are many concepts involved in Java Challenges! In essence, we will continue exploring lambdas and the Function interface the most.

    However, we also have static methods introduced in Java 8 and the private method in interfaces introduced in Java 9. In the invocation of the interface methods, we are using anonymous inner classes too!

    Are you ready for the next Java Challenge? Less introduction, more action, try out this Java Challenge, and master Java concepts by having fun!

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  • Soprano ofNullable stream Java Challenge

    Since Java 9, it’s possible to use Optional with a stream when we need to manipulate values from a List.

    In this Java Challenge, we will explore the use of a stream in an Optional!

    Are you ready to solve this Java Challenge? It’s time to improve your Java skills with this Soprano ofNullable stream Challenge…

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  • Method Reference VS Lambda Java Challenge

    Do you know what the differences are between method references and lambdas?

    In this Java Challenge, we will explore how lambdas and method references behave so that you can really understand how they work!

    Now that you know the main context, it’s time for the Java Challenge!

    It’s time to improve your Java skills with this Method Reference VS Lambda Challenge.

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  • Hidden Dracula Polymorphism Java Challenge

    Polymorphism, the ability of an object to take on multiple forms, is one of the most important Java concepts.

    We might not even be aware we’re using it all the time but when we instantiate an ArrayList and assign it to a variable of the List type, we are using polymorphism.

    It’s a powerful concept because it helps us to decouple responsibilities, therefore, making code more flexible and easier to maintain.

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  • Asynchronous CompletableFuture San Francisco Adventure Java Challenge

    The Completable Future feature is powerful for better performance when running asynchronous methods.

    In Java 5, there is the Future interface, however, the Future interface doesn’t have many methods that would help us to create robust code.

    To solve the limitations of the Future interface, we have the CompletableFuture API with methods that will help us to build reliable high-performant software.

    Now that we had the intro about CompletableFuture, let’s go to the Java Challenge!

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  • Type Erasure Generics Java Challenge

    It’s possible to use type erasure generics in a method with Java. To know how to use generics is important because then you are able to create highly reusable code.

    In the following Java Challenge, you will see the generic type that will be erased by the compiler and then will be replaced by the type we defined at runtime.

    Note also that we are using the extends keyword which means that the generic type will extend the other type.

    Without further ado, it’s time to solve the Java Challenge quiz!

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  • Map, Equals, Hashcode Java Challenge

    Understanding deeply how to use a Map, equals, and hashcode in Java will be a massive help for you to create high-quality code.

    The Map and object reference concepts are not only present in the Java language but in almost all programming languages.

    Therefore, if you master the concept of object references, equals and hashcode, and Maps, you can apply this in other programming languages and master them far more easily.

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  • Optional takeWhile dropWhile Java Challenge

    The Optional concept is present in many programming languages. The main goal of the Optional class is to avoid NullPointerException. It’s much easier to deal with null values when we use the concepts of an Optional.

    In this challenge, we will also explore the takeWhile and dropWhile methods from Java 9. Therefore you will be upgrading your knowledge with Optional, takeWhile, and dropWhile!

    Are you prepared to have fun with this Java Challenge and refine your Java skills?

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  • New Book: “Java Challengers”

    To get the best jobs and create massive value, you need to know Java very well. The newly released “Java Challengers” book is a way for you to challenge yourself with fun code challenges so that you will become a better Java developer.

    This book contains more than 70 well-elaborated Java Challenges that will help you break your limits on your Java skills. Want to challenge yourself and become better? The Java Challenges is the book for you!

    For each Java Challenge you get a full explanation to fully prepare you to beat the Java Challenge!

    To tease you with the Java Challenges book, try out the following challenges and see if you can solve them…

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