Java ↔ JavaScript Transpiler

Converts simple code between Java and JavaScript bidirectionally. Translates common constructs like System.out.println to console.log, static types (String, int, double) to let, Java methods to JavaScript functions, and removes access modifiers (public, private, protected), annotations and throws. Not a full AST parser, uses regex-based rules for quick transformations.

Select "Java → JS" mode at the top. Paste your Java code in the left panel and click "Convert". The result appears in the right panel. Example: Java code "public class Hola { public static void main(String[] args) { System.out.println("Hello"); } }" converts to "function main() { console.log("Hello"); }".

Java → JS handles: System.out.println and System.out.print → console.log, primitive types and String → let (String s → let s), methods → functions, main method → function main(), removes modifiers (public, private, protected), removes annotations (@Override, @Deprecated), removes throws. Does NOT support generics, streams, lambdas, inheritance, interfaces, specific exceptions, or Java APIs like Collections or Swing.

JS → Java handles: console.log → System.out.println, function → public static void, let → String (for simple types), comments. Basic conversion that assumes String types by default. Does NOT handle arrow functions, JSON objects, closures, promises, prototypes, ES6 modules, or modern operators like spread or destructuring.

Java is a compiled language with static typing, running on the JVM. JavaScript is interpreted/dynamic, running in browsers or Node.js. Java uses System.out.println for output, JavaScript uses console.log. Java declares types (String s), JavaScript uses let/const/var. Methods in Java have modifiers (public void), in JavaScript they are functions. Java uses null, JavaScript uses null and undefined. Java supports overloading, JavaScript does not.

Uses regex-based rules, not an AST parser. Limitations: no Java generics (<T>), streams, lambdas, nested classes, inheritance, polymorphism, specific exceptions, standard Java APIs. JavaScript side: no arrow functions, promises, async/await, closures, prototypes, ES6 modules. For complex projects, consider tools like JSweet (Java → TypeScript) or GWT (Java → JavaScript).