We all have those tiny repetitive tasks that take only a few seconds but somehow add up over time. For me, one of them is copying GitHub issues into my Obsidian notes. I usually want the following...

I finally passed the OCP 17 exam! 🎉 Link to badge It took me about 1.5 years from start to finish, with plenty of shorter and longer breaks along the way. 😉 Looking back, I think I could have sp...

🧠 1. Think Like the Compiler, Not Like a Developer As developers, we naturally focus on business logic. The compiler doesn’t. It doesn’t care that your algorithm is correct if: a variab...

Last year I spent a lot of time reading the OCP study guide. I don’t want to leave it unfinished, so my goal for 2026 is to finally pass the exam. These are my reasons. 🧠 I want to finish what I ...

Java provides JDBC interfaces, while database libraries provides implementations - except implementation of DriverManager, which is used to create connection (Q.1) if autocommit is enabled (defau...

Streams byte streams are called *InputStream/*OutputStream (e.g. FileInputStream, BufferedOutputStream), where character streams are *Reader/*Writer (e.g. FileReader, BufferedWriter) ...

Executors be aware whether Executors.newSingleThreadExecutor is used, because running on single thread automatically synchronizes executions, so result will be always consistent (Q.22) ...

Note: Java Platform Module System was introduced in JDK 9 in project Jigsaw. In Java 25 modules would be available through imports like regular classes. Running and packaging simple module Folde...

Let’s consider the following example: var list = List.of(1); var first1 = list.stream().findFirst(); var first2 = list.getFirst(); if (Objects.equals(first1, first2)) { // compiles, just warning i...

try-with-resources can be used only with classes that implement AutoCloseable (also java.io.Closeable which extends AutoCloseable) two or more resources can be defined in one try...