Java List Series
Last updated: June 3, 2026
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.
The List interface is one of Java’s most essential collection types, offering ordered, index-based access to elements with flexible implementations including ArrayList and LinkedList. Understanding how to create, search, sort, and transform lists is a core skill for any Java developer.
This series covers practical List operations from the ground up, organized by task: from picking the right implementation and initializing lists efficiently, through modifying elements, iterating and sorting, finding and filtering, and converting between collection types.
List Types and Fundamentals
- Java List Interface
- List vs. ArrayList in Java
- Java ArrayList vs LinkedList
- Set vs List in Java
- ArrayList vs. LinkedList vs. HashMap in Java
- Guide to CopyOnWriteArrayList
- Working With a List of Lists in Java
Creating and Initializing Lists
- Java List Initialization in One Line
- Difference Between Arrays.asList() and List.of()
- Collections.emptyList() vs. New List Instance
- Immutable ArrayList in Java
- Initialize an ArrayList with Zeroes or Null in Java
- Arrays.asList() vs Collections.singletonList()
Adding, Removing, and Modifying Elements
- Copy a List to Another List in Java
- How to Deep Copy an ArrayList in Java
- Replace Element at a Specific Index in a Java ArrayList
- Inserting an Object in an ArrayList at a Specific Position
- Removing an Element From an ArrayList
- Remove All Occurrences of a Specific Value from a List
- Avoid Inserting Duplicates in ArrayList in Java
Iterating and Sorting Lists
- Ways to Iterate Over a List in Java
- Iterating Backward Through a List
- Reverse an ArrayList in Java
- Sort a List Alphabetically in Java
- Sorting Objects in a List by Date
- Finding Max and Min Date in List Using Streams
- Sorting One List Based on Another List in Java
- Checking If a List Is Sorted in Java
Searching and Filtering Lists
- How to Find an Element in a List with Java
- Finding All Duplicates in a List in Java
- Finding the Differences Between Two Lists in Java
- Java – Get Random Item/Element From a List
- Check if a List Contains an Element From Another List in Java
- Intersection of Two Lists in Java
- Check if a List Contains a String Element While Ignoring Case
- Get Unique Values From an ArrayList in Java
Converting Lists
