Overview

Relevant source files

• CHANGELOG.md
• README.md
• bom/pom.xml
• build-config/pom.xml
• code-parent/pom.xml
• components/pom.xml
• core/pom.xml
• extensions/codeeditor/pom.xml
• extensions/finder/pom.xml
• gwt/pom.xml
• icons/pom.xml
• j2cl/pom.xml
• layouts/pom.xml
• pom.xml
• showcase/pom.xml

This page introduces the patternfly-java project: what it is, what it contains, and how it is organized at the highest level. For detailed build tooling, see Build System and Development. For setting up a local environment or adding it as a dependency, see Getting Started.

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What Is PatternFly Java?

PatternFly Java is a pure Java implementation of the PatternFly design system that generates standard HTML/CSS output conforming to PatternFly's DOM structure and CSS class conventions. It targets browser-based Java runtimesspecifically GWT (Google Web Toolkit) and J2CL (Java-to-Closure-JavaScript transpiler)enabling developers to build PatternFly-compliant web UIs using Java.

Project properties

Property	Value
Group ID	org.patternfly
Current version	0.5.1-SNAPSHOT
Java requirement	Java 21+
PatternFly version	6.4.0
Elemento version	2.4.9
License	Apache License 2.0
JavaScript dependencies	None (except charts)
Supported runtimes	GWT 2.13.0, J2CL
Repository	https://github.com/patternfly-java/patternfly-java

Key characteristics:

• No JavaScript dependencies: All component logic, SVG icons, design tokens, and Popper.js integration are implemented in Java (charts are the exception, requiring the @patternfly-java/charts npm package)
• No bundled CSS: Applications must include PatternFly CSS stylesheets separately
• Fluent builder API: Built on Elemento's type-safe HTML builder API
• Dual platform support: Packages for both GWT (gwt-lib) and J2CL (jar)
• Maven Central distribution: Published with source JARs and API documentation

Sources: README.md1-4 pom.xml29-111 README.md84-86

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Compilation Targets

PatternFly Java supports two Java-to-JavaScript compilation pipelines:

GWT (patternfly-java-gwt): Uses the GWT compiler. Applications inherit the org.patternfly.PatternFly GWT module. Popper.js is injected at runtime via ScriptInjector.

J2CL (patternfly-java-j2cl): Uses the J2CL transpiler with the j2cl-maven-plugin. Popper.js is bundled differently. The showcase application uses this target.

For a detailed comparison, see GWT vs J2CL.

Sources: gwt/pom.xml1-83 j2cl/pom.xml1-62 README.md56-81

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High-Level Architecture

PatternFly Java is organized into distinct layers, from foundational utilities to platform-specific integrations and deployment artifacts.

System architecture module organization and dependencies

Dependency flow:

• Foundation modules (core, tokens, icons, layouts) provide base classes, design primitives, and structural layouts
• Component modules (components, charts) build on the foundation to implement PatternFly UI components
• Extension modules (codeeditor, finder) provide specialized components that extend core functionality
• Platform modules (gwt, j2cl) package the library for specific compilation targets
• BOM manages version consistency across all published artifacts
• Elemento is the core dependency providing the fluent HTML/SVG builder API

Sources: pom.xml113-126 core/pom.xml39-51 components/pom.xml35-51 gwt/pom.xml47-70 j2cl/pom.xml35-44 bom/pom.xml83-200

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Maven Module Structure

The project is organized as a multi-module Maven build rooted at pom.xml19-599 The root POM inherits from org.jboss:jboss-parent:52 and defines the module hierarchy.

Maven parent-child relationships

Key parent POMs:

• patternfly-java-parent (pom.xml19-599): Root aggregator defining plugin versions, profiles, and module list
• patternfly-java-code-parent (code-parent/pom.xml19-105): Shared dependency management for Elemento, JUnit, and PatternFly BOM; inherited by all code modules
• patternfly-java-bom (bom/pom.xml19-256): Standalone BOM for version management; inherits from JBoss parent but not from patternfly-java-parent

Sources: pom.xml23-27 pom.xml113-126 code-parent/pom.xml23-28 bom/pom.xml23-28

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Module Descriptions

Maven Artifact ID	Directory	Packaging	Main Packages / Modules	Purpose
patternfly-java-parent	/	pom	N/A	Root aggregator; defines plugin versions, repositories, profiles (release, showcase, apidoc)
patternfly-java-build-config	build-config/	jar	etc/ resources	Checkstyle config, license headers, import sorting rules
patternfly-java-code-parent	code-parent/	pom	N/A	Dependency management for Elemento BOM, JUnit BOM, PatternFly BOM
patternfly-java-bom	bom/	pom	N/A	Bill of materials; version management for downstream consumers
patternfly-java-core	core/	gwt-lib	org.patternfly.core org.patternfly.popper org.patternfly.style	Base classes (BaseComponent, BaseComponentSVG), Popper.js integration, CSS utilities, ARIA helpers, filter framework
patternfly-java-tokens	tokens/	gwt-lib	org.patternfly.token.Token	Generated enum containing PatternFly design tokens (CSS custom properties)
patternfly-java-icons	icons/	gwt-lib	org.patternfly.icon.IconSets org.patternfly.icon.IconSpecs	Generated icon factory methods for FontAwesome (fas, far, fab) and PatternFly icons
patternfly-java-layouts	layouts/	gwt-lib	org.patternfly.layout.*	Layout components: Flex, Grid, Stack, Gallery, Bullseye, Split
patternfly-java-components	components/	gwt-lib	org.patternfly.component.*	All PatternFly UI components (50+ components)
patternfly-java-charts	charts/	gwt-lib	org.patternfly.component.chart.*	Chart components (Donut, DonutUtilization, Bullet, Pie); hybrid Java + web components architecture
patternfly-java-finder	extensions/finder/	gwt-lib	org.patternfly.extension.finder	Finder extension for browsing hierarchical data
patternfly-java-codeeditor	extensions/codeeditor/	gwt-lib	org.patternfly.extension.codeeditor	Code editor extension with Monaco editor integration
patternfly-java-gwt	gwt/	gwt-lib	org.patternfly.PatternFly (GWT module)	GWT platform integration; aggregates components and layouts dependencies
patternfly-java-j2cl	j2cl/	jar	(packages components + layouts)	J2CL platform integration; JAR packaging with bundled Popper.js externs
patternfly-java-showcase	showcase/	jar	org.patternfly.showcase.*	Demo application built with J2CL; uses -Pshowcase profile

Sources: pom.xml113-126 bom/pom.xml83-200 core/pom.xml30-33 components/pom.xml30-33 gwt/pom.xml30-33 j2cl/pom.xml30-33 README.md107-122

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What the Library Contains

Component Library

The patternfly-java-components module (at components/) contains implementations of PatternFly UI components, organized into packages under org.patternfly.component.*. Components are grouped by function:

• Page Layout: Page, Masthead, PageSidebar, PageMain, PageSection
• Navigation: Navigation, Breadcrumb, Tabs, JumpLinks, ProgressStepper
• Menu & Selection: Menu, MenuToggle, Dropdown, SingleSelect, MultiSelect, SingleTypeahead, MultiTypeahead
• Form Inputs: Form, FormGroup, TextInput, TextArea, FormSelect, Checkbox, Radio, Switch, NumberInput
• Data Display: Table, DataList, SimpleList, TreeView, DescriptionList
• Overlays: Modal, Wizard, Popover, Tooltip, Alert, EmptyState
• Content & Containers: Card, Panel, Accordion, Label, Title

For detailed component documentation, see Component Library.

Layout Library

The patternfly-java-layouts module (at layouts/) provides structural layout implementations: Flex, Grid, Stack, Gallery, Split, and Bullseye.

For layout documentation, see Layout and Container Components.

Icons

The patternfly-java-icons module provides static factory methods in IconSets for accessing FontAwesome (fas, far, fab) and PatternFly icon sets. Icons are returned as PredefinedIcon instances SVG element builders.

For icon details, see Icon System.

Design Tokens

The patternfly-java-tokens module contains the generated Token enum class at org.patternfly.token.Token. Each constant exposes three fields: name (CSS custom property name, e.g. --pf-t--...), value (default value), and var (wrapped in var()).

For token details, see Design Tokens System.

Charts

The patternfly-java-charts module uses a hybrid architecture: Java builder classes (Donut, DonutUtilization, DonutThreshold, Bullet, Pie) that render via custom HTML elements (pfj-chart-*) backed by the @patternfly-java/charts npm package.

Charts require an external npm dependency unlike all other modules. For chart details, see Chart Components.

Sources: README.md88-103 components/pom.xml1-70 layouts/pom.xml1-53 icons/pom.xml1-104

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API Design Pattern

All components follow a consistent fluent builder API pattern built on Elemento's type-safe HTML builder API. Base classes BaseComponent<E extends HTMLElement, B extends BaseComponent<E, B>> and BaseComponentSVG<E extends SVGElement, B extends BaseComponentSVG<E, B>> provide the foundation.

API method categories consistent across all components

Example usage patterns:

Method naming conventions:

• Factory methods: lowercase, named after component (e.g. button(), card())
• Add methods: add<SubComponentName>() (returns parent for chaining)
• Modifier methods: adjective/verb (e.g. flat(), rounded(), disabled()) (returns this)
• ARIA methods: aria<Attribute>() (returns this)
• Event handlers: on<Event>() (returns this)

Sources: README.md128-193

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Common Interfaces and Base Classes

Components share behavior through inheritance and interface composition. This enables polymorphic usage and consistent APIs across the library.

Core component hierarchy and interfaces

Key interfaces and their role:

Interface / Base Class	Package	Implemented By	Purpose
BaseComponent<E, B>	org.patternfly.component	All HTML components	Element management, CSS class manipulation, ARIA attributes
BaseComponentSVG<E, B>	org.patternfly.component	SVG icons (PredefinedIcon)	SVG element builder with path/viewBox management
HasItems<E, C, S>	org.patternfly.component	DataList, Menu, Tabs, TreeView, Navigation, etc.	Add/remove/iterate/update child items; lifecycle handlers (onAdd, onRemove, onUpdate)
HasIdentifier<E, B>	org.patternfly.component	MenuItem, Tab, Tr, NavigationItem, TreeViewItem, etc.	Unique identifier for retrieving item from parent collection
ComponentContext	org.patternfly.core	Child components in HasItems relationships	Key/value storage per component instance
Closeable	org.patternfly.component	Modal, Popover, Alert, Wizard	Close/dismiss lifecycle with onClose() handler registration
Expandable	org.patternfly.component	Accordion, Navigation, TreeViewItem, ExpandableSection	Expand/collapse state with onToggle() handler
Modifiers.*	org.patternfly.style	Various components	Mixin interfaces for single CSS modifier flags (e.g. Disabled, Plain, Compact)
HasValue<T>	org.patternfly.component	TextInput, Checkbox, Switch, FormSelect	Read/write component value
Ordered	org.patternfly.component	Menu, Table, others	Sorted item insertion via custom comparators

For detailed documentation of these patterns, see Component Foundation and Collection Management.

Sources: README.md194-210 CHANGELOG.md51-52

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Where to Go Next

Topic	Page
Maven module structure in detail	Maven Project Structure
Adding patternfly-java to your project	Getting Started
Core architecture and base classes	Core Architecture
All UI components	Component Library
Chart components	Chart Components
GWT vs J2CL comparison	GWT vs J2CL
Build pipeline and CI/CD	Build System and Development