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Java Code Review Guide

The most common Java bugs, security vulnerabilities, and code quality issues — with real examples and fixes for Spring Boot, Jakarta EE, and standard Java.

What makes Java code review important?

Java is statically typed, which catches many errors at compile time — but it still has a unique set of runtime traps. NullPointerException is the most common Java error in production (nicknamed "The Billion Dollar Mistake" by Tony Hoare, its inventor). SQL injection through JDBC string concatenation and XSS in JSP/Thymeleaf templates remain major security risks.

AI code review tools like LearnCodeGuide analyze Java code across all these categories simultaneously, catching issues that take hours to find manually.

Security Vulnerabilities

3 guides
Security

SQL Injection in Java

Security

XSS in Java

Security

Command Injection in Java

Common Bugs

3 guides
Bug

NullPointerException

Bug

Array Index Out of Bounds

Bug

String Comparison Bugs

Code Quality

4 guides
Code Quality

Dead Code

Code Quality

Duplicate Code

Code Quality

Long Methods

Code Quality

Magic Numbers

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Published by LearnCodeGuide Team · Last reviewed: October 2025