#141 · Programming Language Tools Developer Tool

Java Parser

Parse Java source code directly in your browser and extract packages, imports, classes, interfaces, enums, fields, constructors, methods, annotations, and structural metrics without uploading your code.

Developer Input

Java structure analysis

Java source code

package com.example;

import java.util.List;
import java.util.*;

public class UserService {
    private final List<String> users;

    public UserService(List<String> users) {
        this.users = users;
    }

    public int countActive(boolean enabled) {
        if (!enabled) return 0;
        return users.size();
    }
}

Processing mode

Long method threshold

lines

Include line numbers Detect wildcard imports Detect empty members Auto-run while typing

How to use this developer tool

Paste or type the source code in the input editor.
Select the processing mode and adjust the numeric threshold or indentation option.
Enable the checks needed for this task.
Run the tool, review the status and report, then copy or download the result.

What this developer tool does

Java declarations and source structure is produced locally in your browser and remains copy-ready.

Lexically masks strings and comments, balances delimiters, then extracts declarations with scope-aware regular expressions and line mapping.

This browser parser is designed for source inspection and does not replace javac or a full compiler AST.

Example

Input: Paste the included sample source. Output: Run Java Parser to produce a declaration report, validation result, formatted source, conversion, or generated template. The sample is executable and can be replaced with your own code.

Tips for better output

Use complete source files when possible so declarations and scopes can be detected reliably.
Run formatter or viewer output through the relevant validator before committing changes.
For compiler-authoritative results, verify the final code with the target JDK or .NET SDK.

FAQ

How do I parse Java source code online?

Paste Java source code, choose the required structure scope, and run the parser to extract packages, imports, types, members, and source metrics.

Can I extract Java methods without compiling the code?

Yes. The tool performs browser-based source analysis and lists detectable methods and constructors without running javac.

How can I find classes and interfaces in a Java file?

Use Full structure or Types only mode to list classes, interfaces, enums, and nested declarations with line numbers.

Does the Java parser detect annotations and generics?

It detects common annotations and generic type declarations and includes them in the structural report when present.

Why does a Java parser miss some declarations?

Complex syntax, generated code, text blocks, or incomplete source may exceed lightweight regex-based parsing; use a compiler AST for definitive results.

Related developer tools

TypeScript Checker TypeScript Generator TypeScript Formatter TypeScript Converter

Analysis modules

Module	Purpose
Lexical masking	Protects comments and literals during structural analysis.
Source analysis	Java declarations and source structure.
Live metrics	Characters, lines, bytes, status, and measured processing time.

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