Ruby vs Java: Key Differences to Remember for Your Next Project

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Updated Aug 3, 2023 • 16 min read
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Both Ruby and Java are widely popular programming languages that development teams can choose from. Making this decision should be thoroughly considered.

While they share some similarities, such as they’re both object-oriented languages, the differences between Java and Ruby can make or break the success of your next project.

In terms of global use, Github ranked Java as the 2nd most popular programming language in Q1 2022 and Ruby as 8th. They’re both go-to languages for engineers working in startups all the way to the biggest technology companies in the world. While both Ruby and Java are general-purpose programming languages, they work best on different types of requirements.

In this guide, we’ll be going through the features, pros, and cons of Ruby and Java, as well as their similarities and differences. We’ll also look into some quick tips on when to choose one technology over the other.

Language Popularity Comparison From Github

What is Ruby?

Ruby is an open source, object-oriented scripting language built with simplicity as its principal characteristic. It was created in 1995 by Yukihiro Matsumoto and was written in the programming language C.

Ruby is often regarded as easier to comprehend than some of its peers because of its dynamic typing. Its ease of use and speed have made it a popular choice among app developers and one of the leading options when it comes to building web apps rapidly.

Often interchanged by non-developers with Ruby on Rails (also referred to as RoR or Rails to avoid confusion), Ruby and RoR have a different purpose, with Ruby being a scripting language and the latter being a web app development framework.

Ruby supports a broad range of platforms, including Windows, Mac, and Linux. Well-known companies and apps that use Ruby are Shopify, Airbnb, Twitch, Kickstarter and Github, among many others.

To help you decide whether Ruby is the right language for the app you’ll be building, here are its key features, including its pros and cons.

Features of Ruby

  • Open source
  • Pure object-oriented
  • Interpreted
  • Dynamic and duck typing
  • Multi-platform
  • Smart garbage collector
  • Flexible and elegant syntax
  • Can be embedded to HTML

Pros of Ruby

  • Developers can produce high-quality code very quickly, which facilitates rapid development and faster time-to-market. Ruby is an ideal solution for projects under pressure from deadlines or short turnaround times.
  • Ruby’s flexible and easy-to-understand syntax makes it a good option for validating product ideas, prototyping, and MVPs. Engineers can build their first few features or introduce new ones within a relatively short period.
  • Ruby is the ideal programming language for developing web apps, especially with Ruby on Rails, which further simplifies the code and speeds up the overall development process.
  • The design of Ruby constrains developers into its non-opinionated way of coding. While this might be a difficulty for some, it’s broadly seen by the Ruby community as a positive trait, which facilitates a clean code and allows development teams to focus on custom features, dynamic interfaces, and interactivity.

Cons of Ruby

  • Ruby is known as one of the slower programming languages when it comes to runtime speed. This makes Ruby suboptimal for memory-intensive projects.
  • Developers who prefer default or strict rules of opinionated programming languages will need to adjust to its non-opinionated nature.
  • While Ruby has a vibrant community of developers, it’s not as big as Java’s community. One key implication is that access to Ruby talent is more limited.

What is Java?

Java is an object-oriented programming language widely known as a technology suitable for enterprise-grade systems. It was developed at Sun Microsystems (acquired later on by Oracle) by a team led by James Gosling in 1995 (same year as Ruby). Its syntax was inspired by and similar to the C and C++ languages.

Java follows a write once, run anywhere (WORA) concept, which enables Java code to run on systems that support Java without requiring recompilation. Development teams recognize Java as a leading option when it comes to sophisticated and memory-intensive platforms. Well-known companies and apps that use Java are Amazon, Netflix, Google, Uber, and Pinterest, among others.

To help you decide whether Java is the right language for your project, here are its key features, including its advantages and disadvantages.

Features of Java

  • Open source
  • Hybrid object-oriented
  • Interpreted and compiled
  • Static typing
  • Platform-independent
  • Garbage-collection
  • Easy to learn syntax
  • Portable
  • Simple memory management
  • Architecture neutrality
  • Multithreaded

Pros of Java

  • Java is a standard in enterprise computing. While it can be used in a broad range of products (e.g. web applications, customized software), it’s widely recognized as a proven technology for large and complex systems.
  • Java is a programming language that has an intuitive syntax, making it easy to learn. It doesn’t have a lot of syntactic rules and complex structures.
  • Java employs automatic memory management. This eliminates the need for developers to manage memory manually. Java utilizes a garbage collector to recover unused memory, resulting in more reliable and robust Java programs.
  • Java supports multithreading, which allows apps on Java to run several tasks simultaneously. Multithreading enables Java systems to be more efficient and responsive through maximum CPU utilization.

Cons of Java

  • Java consumes memory in a way that makes it slower and performs poorly compared to other native languages, such as C and C++. This is caused by the additional level of compilation and abstraction by the Java virtual machine (JVM). The garbage collector, which requires additional CPU time, also contributes to its relatively sluggish performance.
  • Java code is verbose, which makes the code explicit and reduces its readability. While Java has straightforward syntax, it compromises with complicated codes and lengthy explanations.
  • Many active programming languages today are open-source and free for developers to use. However, Oracle has announced that they'll be charging for the licensing of the Java Standard Edition, which is a significant disadvantage for companies searching for a low-cost option for software development.

Key similarities between Ruby and Java

While Ruby and Java cater to different types of projects, they share several characteristics.

  • Both Ruby and Java are object-oriented, which enables engineers to design around data and its structure and specify the set of functions and logic applied to it.
  • They both have a rich ecosystem of libraries, tools, and resources. Java offers a wealth of libraries, which help development teams in creating any function they require for the platform they're building. Similarly, Ruby offers 'gems', which are tools and libraries that facilitate coding and handle specific functionalities (e.g. credit card integration). JAR files are sort of Java's equivalent of Ruby gems. These are the deployment format for Java, which include classes, icons, property files, and other resources.
  • Both languages have a few frameworks that speed up the work. For Ruby, this includes Ruby on Rails, Hanami, Sinatra, and Grape. Java has Spring, Hibernate, Struts, JSF, and GWT, among many others.
  • Java and Ruby have built-in security features that protect against common security flaws. For instance, Java has bytecode verification and sandboxing, which allows apps to run in a kind of sandbox to detect potential defects. Ruby (along with the Ruby on Rails framework) is also deemed among developers as a highly secure technology, also through the use of security-related gems (e.g. for static analysis).

Key differences between Ruby vs Java

When choosing a technology for your next project, it’s worth paying attention to the differences between Java and Ruby such as:

  • When it comes to compilation, Ruby is interpreted, while Java is compiled to bytecode. Ruby is an interpreted scripting language and is executed directly without first compiling and creating the bytecode. In contrast, applications that use Java need to be compiled for it to run.
  • Ruby variables are dynamically typed, while Java variables are both statically and dynamically typed. When looking at code of both Java and Ruby, the difference can be the typing style. Static typing, which is the case for Java 9 and lower, declares the types that every variable can accept. With Java 10 and higher, as well as with Ruby, which is characterized by the flexibility of dynamic typing, the variables aren’t bound to a certain type, hence the type can change.
  • With Ruby, everything is an object, while in Java, only classes have objects. As a pure object-oriented programming (OOP) language, Ruby defines everything as an object, which includes variables, numbers, methods, and all other user-defined and predefined types. On the other hand, Java doesn’t classify the eight primitive types as objects (int, byte, short, long, float, double, boolean, and char). This is why Java is considered more as hybrid object-oriented, rather than as a pure OOP language.

Quick guide: Ruby versus Java

Here’s a quick guide that compares and contrasts these two technologies.

Ruby Java

What is it?

General-purpose programming language

General-purpose programming language

How is it compiled?


Interpreted and compiled

What is its typing style?



What is its object orientation?

Pure object-oriented programming

Hybrid object-oriented programming

Is it open source?



Is there built-in security?



Ideal for which types of apps?

Small to mid-level web apps

Enterprise-grade systems

What are the frameworks it supports?

Ruby on Rails, Hanami, Sinatra, and Grape

Spring, Hibernate, Struts, JSF, and GWT

How big is its community?

  • 5th most popular language

  • Has a vibrant, but smaller community than Java

  • 3rd most popular language

  • Has a bigger community than Ruby

  • Wider access to talent

Ruby vs Java code comparison

To get a closer look at the difference between Java and Ruby when it comes to the code, here’s a simple example. The Ruby and Java scripts below will print the following two messages into the console:

Hello John!

Hello Jane!

Sample code using Ruby

#!/usr/bin/env ruby

class Welcome
  attr_reader :name

  def initialize(name:)
    @name = name

  def call
    puts "Hello #{name}!"
end "John").call "Jane").call

Sample code using Java

public class Welcome {
    private final String name;

    public Welcome(String name) { = name;

    public void call() {
        System.out.printf("Hello %s! \n", name);

public class Main {
    public static void main(String[] args) {
        new Welcome("John").call();
        new Welcome("Jane").call();

Ruby versus Java: Which one over the other?

Are you still undecided about the programming language for your next project and still at a crossroad? On one hand, there's Ruby with its efficiency and elegance. On the other hand, Java can be used for nearly every kind of project. Here are some quick tips to help you decide when to choose Ruby over Java — or Java over Ruby:

When to use Ruby

  • Ruby is preferable to Java for projects that require flexibility or nimbleness often associated with startups or emerging product ideas. Use Ruby for prototyping or when the product idea is still going through validation. This also makes it a better choice for projects expecting frequent changes or revisions in features and functionalities.
  • Ruby has a clear advantage over Java when it comes to developing web applications, especially when used with the Rails framework.
  • One of the main reasons why developers choose Ruby over Java is that writing a function in Ruby requires less lines of code than in Java. This makes code management easier for development teams, which makes Ruby preferable to teams pressed for time.

When to use Java

  • Java is a better choice over Ruby for sophisticated projects typically associated with enterprise-level requirements. These usually are systems associated with memory-intensive specifications, big data requirements, and complex architecture. Further, opt for Java if the platform interacts with a suite of adjacent systems, such as databases, web services, mainframe backends, etc.
  • When it comes to application performance, Java outperforms Ruby. This makes Java a better option when it comes to apps that are memory-hungry, high-traffic, high-security, and other factors that affect speed and performance.
  • Choose Java over Ruby if you’ll be running the system on your own server, otherwise it’ll be costly to host these types of platforms with a cloud provider.

The right technology for your app

All languages come with their respective strengths and weaknesses. With a wide variety of programming languages, each with its own dedicated community of developers, it’s about making the right technology choices for your project.

Ultimately, when it comes to the Ruby vs Java debate, in most cases, Java is the preferable choice for larger, more complex projects, especially enterprise-grade systems. On the other hand, Ruby is better suited for web apps, especially for startups and businesses still developing their product ideas.

Now that we’ve laid out the key differences between Ruby vs Java, we hope that you'll be able to make a better-informed choice for your next project.

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