Most developers write Java every day without ever seeing what happens before compilation begins.
Tokenization, parsing, semantic analysis — these three stages transform the text you write into something the JVM can actually execute. They're the foundation of every compiler, and yet most of us treat them as a black box.
I built three interactive tools — free and open source — that let you observe each phase live, on real Java code. These aren't simplified simulations: they follow the actual language specifications.
⚙️ The Arcane Tokenizer — Java Tokenizer
Enter any Java code and watch the scanner break it down into lexical tokens: keywords, identifiers, operators, literals. This is the first step of every compiler — the moment raw text becomes structured data.
🌲 The Arcane Parser — Java Parser
Visualize the Abstract Syntax Tree generated by a recursive descent parser. See how a flat sequence of tokens becomes a tree structure with hierarchical relationships — MethodDecl, Block, Expr, Literal.
👁️ The Semantic Eye — Java Semantic Analyzer
Type checking, variable scoping, initialization analysis, return path analysis. The errors the parser can't see, semantic analysis reveals. This is where the compiler starts to understand your code.
Each tool includes bilingual step-by-step explanations (IT/EN) and a coverage section showing exactly what's supported and what's not.
👉 Try the tools: https://eldritch.codes/en/tools
Part of the "Eldritch Codes" series — a comprehensive guide to Java SE 25, explored through the lens of the JVM and the original specs.
Top comments (0)