Get Started with Java
Last updated: September 14, 2019
Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.
Get started with understanding multi-threaded applications with our Java Concurrency guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
Refactor Java code safely — and automatically — with OpenRewrite.
Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.
Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.
Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.
Regression testing is an important step in the release process, to ensure that new code doesn't break the existing functionality. As the codebase evolves, we want to run these tests frequently to help catch any issues early on.
The best way to ensure these tests run frequently on an automated basis is, of course, to include them in the CI/CD pipeline. This way, the regression tests will execute automatically whenever we commit code to the repository.
In this tutorial, we'll see how to create regression tests using Selenium, and then include them in our pipeline using GitHub Actions:, to be run on the LambdaTest cloud grid:
Java is one of the most popular programming languages, often used for building web and enterprise scale applications. This collection of tutorials will help you get started with the basic concepts in Java.
If you are already familiar with the fundamentals, check out the larger Java guide here: Java Tutorial which goes into more detail with each aspect of the language.
Java Language Basics
Before learning about classes and objects, let’s start with the basic syntax of the language.
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Introduction to Basic Syntax in Java
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Introduction to Java Primitives
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Java main() Method Explained
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Control Structures in Java
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A Guide to Java Loops
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Guide to Java Packages
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Pass-By-Value as a Parameter Passing Mechanism in Java
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Varargs in Java
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Guide to hashCode() in Java
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Java Switch Statement
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Guide to the Java forEach Loop
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Immutable Objects in Java
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A Guide to Java Modularity
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Java OOP
Next, let’s dive into the world of object-oriented programming, with practical Java examples.
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Java Classes and Objects
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Concrete Class in Java
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Access Modifiers in Java
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A Guide to Constructors in Java
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A Guide to Creating Objects in Java
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Abstract Classes in Java
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Java Interfaces
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Guide to Inheritance in Java
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Inheritance and Composition (Is-a vs Has-a relationship) in Java
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Method Overloading and Overriding in Java
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Composition, Aggregation, and Association in Java
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Guide to the this Java Keyword
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Guide to the super Java Keyword
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A Guide to the Static Keyword in Java
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The "final" Keyword in Java
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Java Record Keyword
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A Guide to Java Enums
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Guide To Java Optional
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Comparing Objects in Java
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Java equals() and hashCode() Contracts
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Functional Interfaces in Java
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Unnamed Classes and Instance Main Methods in Java
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Callback Functions in Java
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Pattern Matching for Switch
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Sealed Classes and Interfaces in Java
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Functional Programming in Java
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The transient Keyword in Java
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Java instanceof Operator
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How to Make a Deep Copy of an Object in Java
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Object Type Casting in Java
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Static and Default Methods in Interfaces in Java
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Guide to Java Reflection
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Java Strings
Strings are a common data type in Java, representing text. Let’s have a look at how to create and use String objects.
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All About String in Java
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Why String Is Immutable in Java?
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Comparing Strings in Java
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Java String Conversions
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Java toString() Method
Java Exceptions
Exceptions are abnormal behaviors during the execution of a program. Let’s understand what Java exceptions are and how they can help us write less error-prone code.
Java Arrays
It’s time to have a look at our first data structure in Java – arrays.
Java Collections
A more complex type of data structure are collections, which, compared to arrays, have a dynamic size.
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Guide to the Java ArrayList
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A Guide to the Java LinkedList
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Guide to the Diamond Operator in Java
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Comparator and Comparable in Java
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The Basics of Java Generics
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A Guide to HashSet in Java
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A Guide to Java HashMap
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Initialize a HashMap in Java
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A Guide to Iterator in Java
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Converting Between an Array and a List in Java
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Java Streams
Finally, we get to Java Streams – which are not data structures, but wrappers around data sources and allow us to process data more efficiently.
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Introduction to Java Streams
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The Java Stream API Tutorial
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Functional Interfaces in Java
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Guide to Java Collectors
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Java Stream Filter with Lambda Expression
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Java IO
Look at ways to interact with files and other data input/output methods in Java.
Java Development Environment
It’s important to understand the fundamentals of how the Java Virtual Machine and other development tools work.
Of course, there’s a lot more to learn about Java programming, and the development tools and APIs available are changing every day. But with a strong foundation of the basic concepts, you can jump in to building something and always continue learning.
For more tutorials and examples of problem-solving in Java, also have a look at the Java category on the site.
