Code Converter (Python → Java)

Project Overview

Code Converter is a rule-based source-to-source compiler that converts Python code into equivalent Java code. The project focuses on syntax transformation, not error detection, and is designed to work correctly for valid Python programs.

This tool is built using Spring Boot for the backend and a web-based frontend for user interaction.

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Features

• Converts Python code to Java

• Supports:

  • if, elif, else
  • for loops (range)
  • while loops
  • def functions with return
  • Variable assignments
  • print() → System.out.println()

• Handles:

  • and, or, not correctly (outside strings)
  • Nested blocks using indentation

• Rule-based conversion (no AST or ML)

• Proper Java block {} generation

• Error reporting for unsupported data types:

  • ❌ List
  • ❌ Dictionary
  • ❌ Tuple

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🚫 Not Supported (By Design)

• Classes
• Imports
• Exception handling (try/except)
• Global keyword
• Python collections (list, dict, tuple)
• User input handling (input(), int(input()), etc.)
• Error detection (syntax validation) These features are intentionally not supported, as the project is a rule-based converter, not a full compiler or error detector.

⚠️ This compiler assumes valid Python input and focuses only on conversion.

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🛠️ Tech Stack

Backend

• Java
• Spring Boot
• REST API

Frontend

• HTML
• CSS
• JavaScript

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📂 Project Structure

code-converter/
├── backend/
│   └── CodeConvertService.java
│   └── CodeController.java
│   └── CodeTransformApplication.java
│
├── frontend/
│   ├── index.html
│   ├── style.css
│   └── script.js
│
├── README.md

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How Conversion Works

1. Pass 1

   • Collects Python function definitions
   • Separates main code and function bodies

2. Pass 2

   • Converts Python syntax into Java
   • Uses indentation tracking to generate {} blocks
   • Resolves return types
   • Generates final Java class

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Testing

• Tested with 50 different Python test cases

• Includes:

  • Nested if-elif-else
  • Loops inside functions
  • Logical expressions Accuracy Result

Total Test Cases: 50

Successfully Converted: 50

Accuracy: 100% (50/50)

Result:50/50 test cases passed

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▶️ How to Run

Backend

mvn spring-boot:run

Frontend

• Open index.html in browser
• Paste Python code
• Click Convert
• View Java output

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Example

Python Input

def check(x):
    if x > 5:
        return "Big"
    else:
        return "Small"

print(check(10))

Java Output

public class Main {
    static String check(int x) {
        if (x > 5) {
            return "Big";
        } else {
            return "Small";
        }
    }

    public static void main(String[] args) {
        System.out.println(check(10));
    }
}