The Most Widely Used Java Libraries

A typical Java project relies on third-party libraries. This article summarizes the most popular and widely used Java libraries for a variety of different applications. A simple example is also provided for some of them, if it can be found on ProgramCreek.

Java SDK
is surely the #1 widely used library. So the focus of this list is the popular third-party libraries. The list may not not perfect, so leave your comment if you think others should be included.

1. Core

Apache Commons Lang – Apache’s library that provides a host of helper utilities for the java.lang API, such as String manipulation, object creation, etc.

Google Guava – Google’s Core library for collections, caching, primitives support, etc.

(example)

2. HTML, XML Parser

Jsoup – a convenient library to manipulate HTML.
(example)

STaX – Process XML code.
(example)

3. Web Frameworks

Spring – an open source application framework and inversion of control container for the Java platform.

(example)

Struts 2 – most popular web framework from Apache.
(example)

Google Web Toolkit – a development toolkit from Google for building and optimizing complex browser-based applications.

(example)

Strips – a presentation framework for building web applications using the latest Java technologies.

Tapestry – component oriented framework for creating dynamic, robust, highly scalable web applications in Java.

Here is a
comparison of those frameworks.

4. Chart, Report, Graph

JFreeChart – creates charts such as bar charts, line charts, pie charts, etc.

JFreeReport – creates PDF reports.

JGraphT – create graph that contains a set of nodes connected by edges.

5. Windowing Libraries

Swing – a GUI library from SDK.
(example)

SWT – a GUI library from eclipse.

SWT vs. Swing

6. GUI Frameworks

Eclipse RCP.
(example)

7. Natural Language Processing

OpenNLP – a library from Apache.
(example)

Stanford Parser – a library from Stanford University.
(example)

If you are an expert of NLP,
here are more tools.

8. Static Analysis

Eclipse JDT – a library from IBM which can manipulate Java source code.
(example)

WALA – a library that can process .jar file, i.e., bytecode.
(example)

9. JSON

Jackson – a multi-purpose Java library for processing JSON data format. Jackson aims to be the best possible combination of fast, correct, lightweight, and ergonomic for developers.

XStream – a simple library to serialize objects to XML and back again.

Google Gson – a Java library that can be used to convert Java Objects into their JSON representation. (example)

JSON-lib – a java library for transforming beans, maps, collections, java arrays and XML to JSON and back again to beans and DynaBeans.

10. Math

Apache Commons Math – provide functions for math and statistics.

11. Logging

Apache Log4j – most popular logging library.
(example)

Logback – a successor to the popular log4j project.

The Simple Logging Facade for Java (SLF4J) – a simple facade or abstraction for various logging frameworks (e.g. java.util.logging, logback, log4j) allowing the end user to plug in the desired logging framework at deployment time.

12. Office-Complicant

Apache POI – APIs for manipulating various file formats based upon Microsoft’s OLE 2 Compound Document format using pure Java.

Docx4j – a Java library for creating and manipulating Microsoft Open XML (Word docx, Powerpoint pptx, and Excel xlsx) files.

* 1) The list above are based on my own survey combined with personal experience. It is possible that they are not precisely THE MOST popular, but at least well-known.

* 2) I will keep updating this list to make it more complete and accurate. Thanks for your comments.

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