UML Editor (SCD_UML_project)

A desktop UML diagram editor built with Java 17 + JavaFX. You draw diagrams on a canvas, connect them with UML relationships, and save your work as JSON or export it as a PDF.

Built by Zohaib Raffat and Ahmad as a Software Construction & Development (SCD) project.

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What it does

The app opens on a welcome screen where you pick one of two editing modes:

Mode	What you can place
Class Diagram	Classes (attributes + operations), Interfaces, Enumerations
Use Case Diagram	System frame (boundary box), Actors, Use cases

Both modes share the same canvas engine, so you always get:

• Drag to move any element; the connected lines follow it live.
• Click to select, with a highlight, and Delete Selected to remove an element and everything attached to it.
• Right-click a relationship line to delete just that line.
• Editable labels on relationships — click the text field on a line to name it (e.g. multiplicity or role).
• Change Diagram Type to go back to the welcome screen (warns about unsaved changes first).

Relationships

Class diagram	Use case diagram
Association	Association
Aggregation (hollow diamond)	Include
Composition (filled diamond)	Extend
Inheritance (hollow triangle)

Drawing a relationship is a two-click mode: press the relationship button, click the source element, then click the target element. Arrowheads and diamonds are drawn automatically and re-anchor to the element borders as you drag things around.

Save / Load / Export

• Save Diagram → writes a .json file containing every diagram plus every relationship (type, source class name, target class name, label text).
• Load Diagram → clears the canvas and rebuilds the diagrams and their relationships from a .json file.
• Save as PDF → snapshots the canvas and embeds it, scaled to fit, into a one-page PDF via iText.

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Requirements

JDK	17 or newer. Verified working on JDK 25 (Temurin/Homebrew). No separate JavaFX SDK needed — JavaFX comes in as a Maven dependency.
Maven	Not required — use the bundled wrapper (./mvnw). It downloads Maven 3.8.5 on first run.
Network	Needed on the first build to fetch dependencies.
OS	macOS, Windows, Linux. JavaFX pulls the right native classifier for your platform automatically.

This is a GUI application — it needs a real desktop session. It will not run over a plain SSH shell or in a headless container.

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Running it

Quickest path (recommended)

cd UML-Editor
chmod +x mvnw          # first time only — the wrapper ships without the executable bit
./mvnw clean javafx:run

The javafx-maven-plugin puts JavaFX on the module path for you and launches org.example.scd_uml_project.HelloApplication. An 800×600 window titled "UML Editor" appears.

On Windows use mvnw.cmd clean javafx:run (no chmod needed).

From an IDE

Open UML-Editor/pom.xml as a Maven project in IntelliJ IDEA or VS Code, let it import, then run HelloApplication. Because the project is modular (src/main/java/module-info.java), the IDE handles the module path automatically — no --add-modules VM arguments required.

Compiling without running

./mvnw clean compile                        # main sources only — works
./mvnw clean package -Dmaven.test.skip=true # produces target/SCD_UML_project-1.0-SNAPSHOT.jar

./mvnw package and ./mvnw test fail on their own — see Known issues below. Note that -DskipTests is not enough; you need -Dmaven.test.skip=true, which skips test compilation too.

About java -jar

The produced jar is a plain jar: it has no Main-Class in its manifest and does not bundle JavaFX, org.json, or iText. java -jar target/SCD_UML_project-1.0-SNAPSHOT.jar will not work. Use ./mvnw javafx:run or the IDE. Making a runnable jar would require adding a shade/assembly plugin (or javafx:jlink — see the note about iText below).

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Known issues (things that will stop you)

These are real, verified against the current code on macOS / JDK 25.

1. The test suite does not compile — this breaks mvn package and mvn test 🔴

src/test/java/.../HelloControllerTest.java fails testCompile with 5 errors:

Line	Error
23	cannot find symbol: variable loader — the loader is named fxmlLoader; the line Parent root = loader.load(); got merged onto the same line as its declaration
52	cannot find symbol: variable promptForTitle — no such field on HelloController
70, 108	cannot find symbol: method getLastShownAlert() — no such method on HelloController
95	selectedDiagram has private access in HelloController

The test was written against a version of HelloController that exposes test hooks the current controller does not have. This does not affect running the app — compile and javafx:run both succeed. To build a jar, skip tests with -Dmaven.test.skip=true. To actually fix it, either add the missing hooks to HelloController (promptForTitle, getLastShownAlert(), widen selectedDiagram to protected) or rewrite/remove the test.

2. Mixed JavaFX versions in pom.xml 🟠

The POM declares two different JavaFX releases:

javafx-controls, javafx-fxml, javafx-media  →  17.0.6
javafx-base, javafx-graphics, javafx-swing  →  21.0.1

JavaFX expects all its modules to be the same version. Maven's nearest-wins resolution keeps both, so javafx.controls 17 runs on top of javafx.graphics 21. It does launch today, but this is exactly the setup that produces NoSuchMethodError / NoClassDefFoundError at runtime after a dependency bump. Align all six on one version (21.0.1 is the safe choice, since it's what graphics already resolves to).

3. testfx-core is a compile-scope dependency 🟠

org.testfx:testfx-core (and transitively hamcrest and assertj) has no <scope>test</scope>, so a test-only framework lands on the application's runtime module path. testfx-junit5 is correctly scoped; testfx-core should be too.

4. iText is an automodule — jlink/jpackage will fail 🟡

Every build prints:

Required filename-based automodules detected: [itextpdf-5.5.13.3.jar].
Please don't publish this project to a public artifact repository!

itextpdf 5.x has no module-info and no Automatic-Module-Name, so its module name is derived from the filename. module-info.java still does requires itextpdf;, which works for compiling and running but blocks the javafx:jlink goal the POM is otherwise configured for.

5. mvnw ships without the executable bit 🟡

A fresh clone gives permission denied: ./mvnw. Run chmod +x mvnw once (already noted above).

6. Compiler uses -source/-target 17 instead of --release 17 🟡

Warning on every build: "location of system modules is not set in conjunction with -source 17 … may lead to class files that cannot run on JDK 17." Switching the maven-compiler-plugin config from <source>/<target> to <release>17</release> silences it and makes the JDK-17 target real.

Minor

• src/main/resources/zoeb_pic.jpeg (and its duplicate under org/example/scd_uml_project/) is not referenced by any code or FXML — dead weight in the jar.
• ClassDiagram.fxml and UseCaseDiagram.fxml are missing the <?xml version="1.0" encoding="UTF-8"?> prolog that WelcomePage.fxml has. FXMLLoader tolerates it, but it's inconsistent.
• HelloController is a 2,850-line class holding the entire editor. Every relationship type has its own near-duplicate create*Line / adjust*LineToBorders / delete*Line / add*DynamicUpdateListener quartet — the obvious refactor target.

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Project layout

UML-Editor/
├── pom.xml                       Maven build: JavaFX, org.json, iText, JUnit 5, TestFX
├── mvnw, mvnw.cmd, .mvn/         Maven wrapper (Maven 3.8.5)
└── src/
    ├── main/
    │   ├── java/
    │   │   ├── module-info.java  module org.example.scd_uml_project
    │   │   └── org/example/scd_uml_project/
    │   │       ├── HelloApplication.java    Entry point — loads WelcomePage.fxml
    │   │       ├── WelcomeController.java   Diagram-type picker
    │   │       ├── HelloController.java     The editor: canvas, all tools, save/load/PDF
    │   │       ├── DiagramBase.java         Interface: toJSON() + getClassName()
    │   │       ├── ClassDiagram.java        \
    │   │       ├── InterfaceDiagram.java     |  Draggable Pane subclasses
    │   │       ├── EnumerationDiagram.java   |  rendered on the canvas
    │   │       ├── UseCaseDiagram.java       |
    │   │       ├── Actor.java               /
    │   │       ├── ClassData.java           \
    │   │       ├── InterfaceData.java        |  Plain data holders backing
    │   │       ├── EnumerationData.java      |  each diagram type
    │   │       ├── UseCaseData.java          |
    │   │       ├── ActorData.java           /
    │   │       ├── Relationship.java        Type + source + target + label
    │   │       └── RelationshipNode.java    Group wrapper placed on the canvas
    │   └── resources/org/example/scd_uml_project/
    │       ├── WelcomePage.fxml
    │       ├── ClassDiagram.fxml            Left toolbar: Class/Enum/Interface + Comp/Inh/Agg
    │       └── UseCaseDiagram.fxml          Left toolbar: Actor/Use Case/Include/Extend/Frame
    └── test/java/org/example/scd_uml_project/
        └── HelloControllerTest.java         TestFX — currently does not compile (issue #1)

ClassDiagram.fxml and UseCaseDiagram.fxml both bind to the same HelloController. Its initialize() only touches the buttons that exist in both files (btnSave, btnLoad, btnDelete, btnChangeDiagramType, canvasPane), which is why one controller can serve both screens.

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Suggested fix order

1. Align the JavaFX versions (issue #2) — cheapest, biggest reduction in future breakage.
2. Scope testfx-core to test (issue #3).
3. Fix or delete HelloControllerTest so ./mvnw package works unaided (issue #1).
4. Switch to <release>17</release> (issue #6).
5. Add a shade/assembly plugin if a double-clickable jar is wanted, or replace iText 5 with a real JPMS module (e.g. com.itextpdf:itext-core 7.x / PDFBox) to unlock javafx:jlink (issue #4).