How to Create Online Compiler for Java 2023

How to Create Online Compiler for Java

Coding can be a challenging and drawn-out process, making it easy to overlook compilation flaws that could degrade the quality of the end product. To reduce the strain of the procedure and improve the quality of the code, development tools have been implemented.

To increase developer efficiency, these resources are available online and as desktop programmes. One of the easiest programming languages to use and implement is Java.

Errors, though, are unavoidable. To help prevent errors, online Java developer tools like an IDE, code editor, compiler, and interpreter are available. This essay will concentrate on the development of an online Java compiler to aid developers in the process.

Without initially setting up your computer, do you want to learn Java programming? We’ll also take a look at several online Java tools, including the Java Compiler, that, among other things, let you edit, develop, debug, and run Java code.

The functionality of an online Java compiler can vary from a straightforward converter that turns Java files into class files to a complete cloud-based online Java IDE that can be used to manage Java projects.

How to Create Online Compiler for Java

What is a Java compiler?

Because Java is a tightly typed language, variables must contain the correct kind of information. An improper data type cannot be stored in a variable in a strongly typed language.

The Java programming language does a great job of incorporating this safety feature. The Java compiler is in charge of checking the variables for any errors in data-type holding. Run-time exceptions may occasionally happen, which is necessary for Java’s dynamic binding functionality.

In order to have some flexibility, some exceptions are allowed in the data type that a variable can contain, since when a Java programme runs, it might introduce new objects that didn’t exist before.

Other than the comments, the Java compiler sets a filter for those parts of the code that will never compile. The compiler leaves the comments alone and does not parse them. Three sorts of comments are supported by Java code within programmes.




Anything that comes before //, between // and //, or between // and ** is ignored by the Java compiler.

It is designed to be a bytecode compiler and severely checks any syntax errors; from an actual program file, it produces a class file that is entirely written in bytecode.

The Java compiler, which is regarded as the initial level of security, is the first line of defense and is responsible for verifying variables for the correct data type.

A bad data type can have serious external and internal effects on the programme. The compiler also looks for any code that attempts to enforce private classes or other restricted pieces of code.

It prevents unauthorised access to crucial data, classes, or code. The bytecodes and class files produced by the Java compiler are platform- and architecturally neutral, don’t need the Java Virtual Machine to run, and may be used on any device.

How to Create a Java Compiler Online

The creation of a compiler for your project is a laborious undertaking. In this article, we’ll demonstrate how to use Judge0 and ReactJs to construct your own custom, very straightforward online compiler in fewer than 200 lines of code.

Judge0 is an open-source, scalable online code execution system that may be used to develop a wide range of applications, including platforms for competitive programming, online code editors, educational and employment platforms, etc.

Judge0 supports more than 50 different languages, and if you want to add more, you can consult the official documentation and add any language you require. We’ll create a compiler that supports C, C++, Python, Java, and four other languages.

You are urged to follow the instructions exactly as written and to take great care with each step. Even if it seems excessively complicated, we can divide the design of an online code editor and compiler into two parts.

  • An API running on the backend server will accept a piece of code and a language as input and, after running the code on the server, output the result.
  • The front-end code editor allows us to choose the language and edit and modify the code. After that, we can publish a request to the backend API and display the response on the website.

Figure Content

  • Get your API key.
  • Design a React app.
  • Building Your Components

Steps to follow:

Obtain an API key:

Visit to obtain a free API key.

Build a React app:

  • To construct your React project, adhere to the procedures below.
  • create-react-app npx my-app
  • My-App cd
  • npm begin

Producing composites:

Let’s start by making a compiler folder. Files pertaining to the compiler will be kept in this folder.

Make a file in Compiler called Compiler.js.

Let’s break down the code

  • Four states have been used.
  • It is handled by the user-provided source code.
  • Once the code has been submitted, the judge0 compiler’s output is handled by output.
  • Language controls the language into which we want to compile our source code, and user input controls any standard input provided by the user.
  • The initial pull request Make your entry for the judge0 compiler, and then send back a special token.
  • Using the unique token in our second fetch request, we retrieve the output or result of the code we supplied.
  • In the render method, there is some JSX.


The ‘Component’ package from React and the Compiler.css file are being imported.

How to Create Online Compiler for Java

employing a constructor to set the component class’s state after inheriting it from the compiler.


How to Create Online Compiler for Java

The following objective is to record the events that have occurred and their goal value. Any user input is similarly documented as a user event.


The first objective at hand is to discover the language of the programming language that our compiler should be able to identify.

The language id in this instance is 62, and it is Java.

How to Create Online Compiler for Java

Next, we post the aforementioned data using a REST call and the API key.

How to Create Online Compiler for Java


The response—whether our entered details have been accepted or not—is awaited after submission of the aforementioned compiler details.

A unique token is returned from the first fetch request, which also creates our submission to the judge0 compiler.

Using the unique token in our second fetch request, we retrieve the output or result of the code we supplied.

How to Create Online Compiler for Java

As a result of the preceding GET call’s output giving us results in JSON format, we now launch the React app and provide its contents as JSON.

How to Create Online Compiler for Java The compiler’s answer is then displayed. The compiler throws an exception if it discovers any errors.

The user creating the compiler is then given the opportunity to enter information and make choices regarding the compiler they are about to develop using a form that is created. Every time a new set of compiler details needs to be accepted; the function render () is invoked. This function stores the form entries. In the render method, there is some JSX.

How to Create Online Compiler for Java

Here is where the compiler’s functionality is located. We have added the ability to execute C, C++, Python, and Java. Let’s add a new file to the compiler folder called Compiler.css.

How to Create Online Compiler for Java

As a result, we used judge0 to build a straightforward online compiler in React. You can also use this source to run your programme and create a compiler.

How to Create Online Compiler for Java



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