Java

This Java programming series goes from first classes to production Spring Boot apps. It has more than seventy posts, so it works as a full course.

Early posts cover the language and collections. Later, JDBC fundamentals and JPA and Hibernate add data access. Finally, testing Spring Boot apps ties it all together.

74 articles

28/05/2023 11 min read

Utility Classes: Objects, Math, Random, and UUID

Executive Summary: The JDK’s utility classes cover null-safe checks, exact math, random numbers, and IDs. I’ll walk through…
07/05/2023 11 min read

Date and Time API in Java (java.time)

Executive Summary: The java.time API separates human dates from machine timestamps. I’ll cover LocalDate and LocalDateTime for calendar…
01/04/2023 10 min read

Optional in Java: Avoiding NullPointerException

Executive Summary: Optional in Java is a container that is either present or empty, meant for query results…
05/03/2023 10 min read

Streams API Part 3: Parallel Streams and Pitfalls

Executive Summary: Parallel streams split work across the shared ForkJoinPool, and they only help under specific conditions. I…
04/02/2023 10 min read

Streams API Part 2: reduce, collect, and Collectors

Executive Summary: Java streams end in a value through reduce or collect. I cover reduce with an identity…
07/01/2023 9 min read

Streams API Part 1: map, filter, and forEach

Executive Summary: A Java stream is a one-use, lazy pipeline over a source such as a collection, array,…
10/12/2022 10 min read

Lambda Expressions and Functional Interfaces in Java

Executive Summary: A Java lambda implements the single abstract method of a functional interface. I cover the standard…
19/11/2022 9 min read

Creating Custom Exceptions and Best Practices

Executive Summary: Create a custom Java exception when a failure has domain meaning that callers need to handle…
16/10/2022 10 min read

The Java Exception Hierarchy: Checked, Unchecked, and Error Handling by Design

Executive Summary: Every Java exception descends from Throwable, split into Errors, checked exceptions, and unchecked RuntimeExceptions. I cover…
18/09/2022 11 min read

Generics in Java: Type Safety, Bounded Types, and Wildcards

Executive Summary: Java generics give you type-safe, reusable code with no casts. Here I cover generic classes and…
14/08/2022 8 min read

Choosing the Right Collection: Performance and Trade-offs

Executive Summary: Choosing a Java collection comes down to access pattern, ordering needs, key types, and data size.…
10/07/2022 10 min read

Collections Framework Part 2: Map and Queue

Executive Summary: Java Maps store values by unique keys and Queues control processing order. I cover HashMap, LinkedHashMap,…
11/06/2022 11 min read

Collections Framework Part 1: List and Set

Executive Summary: The Collections Framework separates interfaces like List and Set from their implementations. I explain when to…
22/05/2022 13 min read

Practice: Model a Library System with OOP (Part 2: Behavior and Persistence)

Executive Summary: Part 2 of the library system project adds behavior and persistence to the Java domain model.…