Cs Maven

Fixing NullPointerException in Mockito When Using when().thenReturn()

By admin April 22, 2025

Are you encountering a NullPointerException while stubbing methods with Mockito's when().thenReturn()? This common issue often arises when chaining method calls on mocked objects. Let’s explore how to resolve this efficiently.…

Java Threads: wait() vs sleep() – Key Differences and When to Use Each

By admin April 20, 2025

Understanding the differences between wait() and sleep() in Java is crucial for writing efficient, thread-safe applications. While both methods pause thread execution, they serve distinct purposes. This post breaks down…

Green Threads vs. Virtual Threads in Java: What’s the Difference?

By admin April 16, 2025

Java’s approach to concurrency has come a long way. With the arrival of virtual threads in Java 19, there’s renewed interest in how they compare to the older green threads…

Why Java Allows Code Execution in Comments with Unicode Escapes

By admin April 16, 2025

Ever seen a Java comment that somehow runs code? It’s not magic — it’s due to a lesser-known behavior in how Java handles Unicode escapes. Let’s explore why this happens,…

How to Fix java.lang.UnsupportedClassVersionError — Step-by-Step

By admin April 16, 2025

Getting hit with java.lang.UnsupportedClassVersionError when you run your Java program? This error usually means your code was compiled with a newer Java version than your system can handle. Don’t worry…

Fixing “Required Request Body is Missing” in Spring Boot: A Complete Guide

By admin April 14, 2025

Meta Description: Running into the "Required request body is missing" error in Spring Boot? Learn what causes it and how to fix it using @RequestBody, @RequestParam, and proper content headers.…

Fixing GitLab CI Integration Tests for Spring Boot with PostgreSQL in Docker

By admin April 10, 2025

❌ The Problem You’ve got a Spring Boot application using PostgreSQL in Docker. Everything works locally, but in GitLab CI, integration tests fail with: Connection refused: Cannot connect to PostgreSQL…

Fixing “Cannot Resolve Symbol” in IntelliJ Even When Code Compiles

By admin April 10, 2025

One of the most frustrating issues developers encounter in IntelliJ IDEA is the "Cannot resolve symbol" error—especially when the code compiles and runs just fine. If you've seen red underlines…

LeetCode Problem 98: Validate Binary Search Tree(BST) Solution in C++, Java, Python

By admin April 10, 2025

🔍 Problem Overview You’re given the root of a binary tree—your task is to determine whether it’s a valid Binary Search Tree (BST). BST Definition: Left subtree nodes < current…

LeetCode Problem 91: Decode Ways

By admin April 10, 2025

The Decode Ways problem (LeetCode #91) challenges us to determine the number of ways an encoded message, represented as a string of digits, can be decoded into letters using the…

LeetCode 79: Word Search – DFS Solution Explained (C++, Java, Python, C#)

By admin April 10, 2025

Solve LeetCode's Word Search problem efficiently using Depth-First Search (DFS) with backtracking. This comprehensive guide provides optimized code implementations in four languages, complexity analysis, and a step-by-step breakdown of the…

LeetCode 76: Minimum Window Substring – Sliding Window Solution in C++, Java, Python & C#

By admin April 10, 2025

What Is the Minimum Window Substring? The Minimum Window Substring problem asks: Given two strings s and t, find the smallest substring of s that contains all characters of t…

OpenCSV vs Apache Commons CSV vs SuperCSV

How to Iterate Over a JSONObject: 3 Proven Methods (2024 Guide)

How to Exclude Fields in JSON Serialization (But Not Deserialization) Using @JsonIgnore

Gson Field Exclusion Without Annotations: The Complete Guide

Upload Files and JSON in Postman: Complete Spring MVC Guide

OpenCSV vs Apache Commons CSV vs SuperCSV

How to Iterate Over a JSONObject: 3 Proven Methods (2024 Guide)

Fixing NullPointerException in Mockito When Using when().thenReturn()

Java Threads: wait() vs sleep() – Key Differences and When to Use Each

Green Threads vs. Virtual Threads in Java: What’s the Difference?

Why Java Allows Code Execution in Comments with Unicode Escapes

How to Fix java.lang.UnsupportedClassVersionError — Step-by-Step

Fixing “Required Request Body is Missing” in Spring Boot: A Complete Guide

Fixing GitLab CI Integration Tests for Spring Boot with PostgreSQL in Docker

Fixing “Cannot Resolve Symbol” in IntelliJ Even When Code Compiles

LeetCode Problem 98: Validate Binary Search Tree(BST) Solution in C++, Java, Python

LeetCode Problem 91: Decode Ways

LeetCode 79: Word Search – DFS Solution Explained (C++, Java, Python, C#)

LeetCode 76: Minimum Window Substring – Sliding Window Solution in C++, Java, Python & C#

OpenCSV vs Apache Commons CSV vs SuperCSV

How to Iterate Over a JSONObject: 3 Proven Methods (2024 Guide)

How to Exclude Fields in JSON Serialization (But Not Deserialization) Using @JsonIgnore

Gson Field Exclusion Without Annotations: The Complete Guide