Open Source General Purpose Libraries in Java

Java library for console input, similar to GNU readline. Line editing, history, completion, syntax highlighting, password masking; cross-platform. Documentation at jline.

Replacement for pre–Java 8 date/time classes. Multiple calendar systems, time zones, duration, period, interval, and formatting. Maintained; users on Java 8+ are encouraged to migrate to java.

Java APIs for Microsoft document formats: Excel (HSSF/XSSF), Word (HWPF/XWPF), PowerPoint (HSLF/XSLF), Outlook (HSMF), OLE2/POIFS, and OOXML. Supports both legacy binary and Office Open XML.

Set of micro-frameworks and utilities for Java: JSON, HTML parser (Lagarto, Jerry), HTTP client, email, bean manipulation, Props, Petite DI, Db, Proxetta. Lightweight and fast.

Schema-based parser and composer for CSV and fixed-width flat files. Schema in XML or Java; convert between formats; stream-based for large files.

Web-based mind map tool for enterprises and education. Self-hosted; Java backend, separate frontend repo; same codebase as WiseMapping. com.

GPL Java utilities: CSV, Base64, circular buffers, MD5, significant figures, command-line parser, MD5, string helpers, and more.

Java Bean to Java Bean mapper that recursively copies data between objects. Supports property mapping, complex types, bi-directional and recursive mapping via XML or API; project recommends migrating to MapStruct for new use.

Library to convert Java objects between types (including parameterized). Primitives, arrays, collections, beans; 40+ converters; JDK 1. 4/1.

Windows Java launcher alternative to javaw. exe. INI for classpath, main class, VM args; custom executable name, icon, splash screen; DDE, Windows Service wrapper; source on GitHub.

Client, protocol, and server for running Java from the command line without JVM startup overhead. Server in Java, client in C; repo maintained by Facebook (now archived).

ETL and script execution tool. Simple XML scripts; use SQL or scripting languages per data source; cross-database ETL, transactions, flexible error handling.

Multi-format 1D/2D barcode image library in Java: encode/decode, mobile and desktop. Ports to other languages; maintenance mode, patch-driven.

Java library to generate barcodes for display or print. Multiple formats supported; output as PNG, GIF, JPEG, SVG, or as a Swing component.

Flexible Java barcode generator. Integrations for Apache FOP, Xalan, SAXON, and servlets; output to SVG, EPS, Java2D, or bitmaps.

Colt is a Java library suite for high-performance scientific and technical computing, originally developed for CERN workloads. It provides dense and sparse matrices, linear algebra decompositions, statistics, random number generation, and concurrent utilities for numerical applications. The distribution bundles core modules such as cern.

Java architecture for large-scale distributed agent systems (DARPA research). Core runtime plus demonstration, visualization, and management components.

Java library to map CSV files to and from POJOs. No runtime dependency on the library in your beans; extensible parsers and builders.

Java framework to map, parse, and unmarshall CSV into POJOs. Declarative mapping via XML or Xdoclet; requires J2SE 1. 5.

Java API to query Google Desktop Search (COM Query API) from Java. Full-text search over email, files, chats, and web history; Windows only.

Pure Java implementation of DCOM (MSRPC) for interoperability with COM components. No JNI; supports COM automation, server callbacks, and Windows registry CRUD. Platform-independent.

Runtime that discovers and loads plug-ins via manifests. Registry of extension points and extensions; lazy loading so unused plug-ins incur no memory or performance cost. Eclipse-inspired, decoupled from Eclipse.

Automatic number plate recognition (ANPR) using AI, machine vision, and neural networks. Implements plate detection, character segmentation, normalization, and recognition.

Framework for Java Active Objects: message-based, asynchronous communication between objects. Thread assignment via XML descriptor; no explicit Thread or synchronization in application code.

XML-based configuration for Java apps. Single repository of config files, multiple environments, and centralized variable management to avoid duplication.

STL-like functionality for Java: functors, predicates, and utility algorithms for collections. User-derivable implementations (e. g.

Genetic algorithms and genetic programming library for Java. Modular design, grid support, pluggable operators; easy to use out of the box.

Neural network framework: central engine, linkable components, GUI editor, distributed training. Supports supervised and unsupervised learning, multiple architectures, and scripting.

Apply SQL-like queries to Java object collections: search, order, and group. Use when an RDBMS is too heavy or impractical; each object is a row, methods/fields are columns.

Free Java packages for scientific computing: abstract math, linear algebra, statistics, wavelets, Newtonian mechanics, chart components, MathML DOM.

Java authentication and authorization framework. Granular, manageable permission scheme for multi-user applications.

Extensible image processing framework: plug-in algorithms, MarvinEditor GUI, video frames, multithreading, and performance analysis.

Java class library: Syslog logging, JDBC connection pool, lightweight app server (PAS), object pooling, Base64, blocking queues, mutex locks.

Bytecode transformer: run Java 5 classes on JVM 1. 4. Supports generics, annotations, enums, autoboxing, for-each, varargs, concurrency utilities.

Anthill OS was a build management server from UrbanCode that coordinated checkouts, builds, and artifact publishing across teams. It tagged the repository with build numbers and updated project sites with latest artifacts. UrbanCode was acquired by IBM; AnthillPro was retired in 2018 and replaced by IBM UrbanCode Build.

Non-intrusive Java framework for bidirectional POJO relationships. Simplifies domain models by maintaining referential integrity and opposite-side updates automatically. Dual-licensed (GPL and commercial).

Context programming library: stack-like allocation (PoolContext), transparent concurrency (ConcurrentContext), thread-local context (LocalContext). Also provides struct/union for C interop, generic linear algebra, dimension-checked physical quantities, and a fast real-time XML parser.

Prevent multiple instances of the same Java app per user. Locks and communication channels shared between JVM instances; J2SE 1. 4+.

Call native DLL methods from Java without JNI. Supports structs, Strings, primitives, byte/char arrays, and output parameters. Windows only.

Unified access to content repositories: JCR (JSR 170), Subversion, and file-system. Metadata, revisioning, branching and merging; POJO injection, search, Velocity templates.

ZIP and archive access beyond java. util. zip: CP437 names, virtual filesystem, update single entries, directory support, JFileChooser.