Released jSparrow Rules

Automatic Java Refactoring Tool

Maintain and modernize your Java source code with ease

jSparrow in 40 words

jSparrow is an automatic java refactoring tool for programmers and IT-managers who appreciate (value) good software quality.

jSparrow is a fast-paced Java tool that not only shows you what’s wrong but finds internal flaws in software code and fixes them automatically


How many comparators will order the list alphabetically?

code example

How many comparators will order the list alphabetically?

Correct answer is A).

The Comparator instance “natural” is the only one in this example that orders the list in alphabetical order. The instance “lambda” has reversed order, since s2 is the element on which “compareTo” is called on. Have a look at Use Comparator Methods – it is a jSparrow rule that automatically transforms such lambda expressions into static Comparator method calls.

jSparrow benefits

jSparrow Automatic Java Code Refactoring Benefits List

Automatic Java Code Refactoring

Less repetitive work

Repetitive work is with jSparrow unnecessary; through quick and secure maintenance you will have more time to implement new functionality.

Secure Java upgrade

jSparrow can also upgrade your software to more secure and performant versions.

Increase readability

jSparrow can improve readability - making code easier to be read by many and enable managers to expand their software engineering team.

Unique preview mode

Additionally, jSparrow is the only maintenance tool which allows you to preview your original source with the refactored code before making any committing decisions.

jSparrow Business Brochure [PDF]

Rule based approach

jSparrow is rule-based; the tool can find and fix a wide variety of problems in Java sources. Currently, there are over 70 rules.

These rules are designed to apply coding conventions, remove bugs and code smells, improve readability and modernize Java codebase.

Our documentation page has detailed description of all the rules.

Configurable Profiles

jSparrow gives you a hand as you decide what's more important to you: improving readability, performance, old language constructs, formatting, coding conventions or all together.

To categorize and/or filter, you can select and group jSparrow rules as profiles.

Profiles can be exported and imported and profiles also ensures that your company standards will be kept.

Proof of agility

We saved approximately 494 hours, 55 minutes of working hours by running jSparrow on org.eclipse.mdm.

We also ran jSparrow on 50+ Open Source projects on GitHub.

See our results and statistics.


An infrastructure solution

jSparrow is available for Eclipse, Maven, and GitHub.

Full User Control

User always stays in control with jSparrow's rule-based approach. User can select rules and preview the original- and the refactored code side-by-side. To increase control: the new changes will only be implemented when told to.

When user owns a license, the changes can be confirmed and applied to the selected files.


jSparrow is Reliable

Before the jSparrow team implements an automatic rule, the findings are thoroughly tested with all corner cases. Only those methods that can be replaced error-free by new ones are implemented as rules in jSparrow.

Your software, refactored with jSparrow, will be based on solid practices and methods to increase protections against cyberattacks and unauthorised queries.

What is Refactoring?

Code refactoring is maintaining, modernizing, improving readability, boosting performance, or/and increasing the security of the software - without changing the external functionality of the software or program.

jSparrow can do this for you. Automatically.

Local License Server

If your development environment has restricted access to the internet or your company prefers to manage the licenses internally, a standalone server can be set up for jSparrow. For more information please contact us: info@jSparrow.eu


Need help or have questions?

You can either mail to support@jSparrow.eu, use our contact form or try our improved chat bot!

jSparrow is available for:

Refactor in 3 steps

Illustration and screenshots of jSparrow tool

Import project(s) to Eclipse IDE

jSparrow can refactor: Java 1.1, Java 1.2, Java 1.3, Java 1.4, Java 5, Java 6, Java 7, Java 8, Java 9, & Java 10

Right click the project's folder > jSparrow > Select Rules

Replace For-Loop with Stream::forEach - is only one example of a rule. jSparrow has +75 rules.

Compare sources & accept changes

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Average Amount of Hours Saved
Average Amount of Issues Fixed


In the past, repetitive maintenance work could only be done manually but now this is an automated task of jSparrow. As a result your IT-team can finally focus on implementing new business-features and improve the external functionality of your product or/and your system.

When you run jSparrow on your system source, jSparrow will show you side by side a comparison of your original source and the improved source which jSparrow automatically adopted and maintained for you. This allows you to stay certain that there are no hidden actions and no surprises.

Once you decide to integrate jSparrow‘s rule-based changes, you will save months of maintenance effort, and therewith reduce technical debt effectively.

Refactor your Java source with jSparrow – automatically.

Christmas Images

These images were part of a jSparrow Christmas calendar


Authorized Resellers and International Distributors

EasiRun jSparrow Partner in Project

EasiRun is our Distributor and Partner in Projects Visit EasiRun