#137 · Programming Languages Developer Tool

Java Checker

Check Java source for unmatched delimiters, missing semicolon patterns, package and import placement, public-class filename consistency, naming conventions, debug output, and version-sensitive features. The static checks run locally in your browser.

Developer Input

Source code

Java Checker Input

package com.example;

public class Test {
    public static void main(String[] args) {
        System.out.println("Hello")
    }
}

Report Format

Expected File Name

Check delimiters Check semicolons Check naming conventions Check public class filename Detect debug output Auto-run while typing

How to use this developer tool

Paste Java source.
Choose a report format.
Enter the expected .java filename.
Run the checker.
Resolve findings and confirm with javac or an IDE.

What this developer tool does

It performs static text-based checks and extracts packages, imports, types, and methods. It also detects records, text blocks, and switch expressions for version guidance.

Protect literals and comments → match delimiters → extract declarations → run line heuristics → compare public class and filename → report severity.

Use javac or an IDE for authoritative compilation. Missing-semicolon detection is heuristic.

Example

Input

System.out.println("Hello")

Result

WARNING JAVA101 line 1: Possible missing semicolon.

Tips for better output

Match each public class to its file name.
Treat semicolon warnings as prompts for manual review.
Compile after any automated formatting or conversion.

FAQ

How do I check Java syntax errors online?

Paste Java source and run the checker for common structural errors and warnings.

How can I find unmatched braces in Java code?

Delimiter checks track braces, brackets, and parentheses outside strings and comments.

Why must a public Java class match the file name?

Java normally requires a public top-level class to use the same .java filename.

How do I detect missing semicolons in Java?

Enable semicolon checks; likely statement lines without semicolons are reported.

Can this Java checker replace javac compilation?

No. It is a static browser checker and cannot replace the Java compiler.

Related developer tools

TypeScript Checker TypeScript Generator TypeScript Formatter TypeScript Converter

Java checks

Structure	Package, imports, types
Syntax heuristic	Delimiters and semicolons
Style	Naming conventions
Version	Records, text blocks, switch expressions

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