VisuStruct

VisuStruct is a structure-chart editor for Nassi–Shneiderman diagrams (desktop, Kotlin / Swing).

Under Settings → Languages the user interface can be set to any of 21 languages aligned with VisuStruct-swift (English, German, Spanish, French, Italian, Polish, Turkish, Korean, Japanese, Greek, Ukrainian, Arabic, Russian, Hebrew, Dutch, Swedish, Danish, Norwegian Bokmål, Chinese Simplified/Traditional, European Portuguese). Stored as uilanguage in visustruct.properties (e.g. zh_Hans, pt_PT). UI strings are synced from the Swift app where keys overlap: python3 tools/sync_java_messages_from_swift.py (map: VisuStruct-swift/tools/java_swift_i18n_map.json). Desktop-only labels may still fall back to English.

Lineage: Based on the open-source project kekru/struktogrammeditor (Kevin Krummenauer, MIT). Copyright and terms: LICENSE.

Website: visustruct.org · Repository: github.com/code4teaching/VisuStruct

git clone https://github.com/code4teaching/VisuStruct.git

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Changes in 1.2.3 (summary)

• Kotlin: full migration of production code; Java reference under src/main/java-reference/; tests still Java.
• i18n: localized element editor and dialogs; tools/resync_message_bundles.py when Swift repo is absent.
• UI: one-touch expandable element-editor split.

Full notes: release-notes/v1.2.3.md.

Changes in 1.2.2 (summary)

• Languages: 21 UI languages (VisuStruct-swift); tools/sync_java_messages_from_swift.py.
• CI: GitHub Actions build passes again (headless-safe drag-and-drop init for tests).

Full notes: release-notes/v1.2.2.md.

Changes in 1.2.1 (summary)

• Simulation: true/false branch selection by case name; reset (Stop) for new input on rerun; highlight mode and play speed under Settings → Simulation…; sidebar layout (input always visible, current block shows instruction text).
• Save: pending element-editor text applied before save; more reliable save dialog on macOS.
• Code generator: structure chart text as comments off by default.

Full notes: release-notes/v1.2.1.md.

Changes in 1.2.0 (summary)

• Simulation (prep): Kotlin in the Maven build; SimulationDocument and related types plus XML decode aligned with the existing diagram file format; Struktogramm.toSimulationDocument() exports the current editor state for a future step() engine (no simulation UI yet).

Full notes: release-notes/v1.2.0.md.

Changes in 1.1.4 (summary)

• Diagram: canvas view zoom with ⌘+ / ⌘− (macOS) or Ctrl+ / Ctrl− (Windows/Linux); no block resize via mouse wheel anymore.
• Tabs: prompt to save / discard / cancel when closing a diagram with unsaved changes; dirty state shown in the tab header (not as * in the title).
• Code: removed long blocks of commented-out legacy code (especially Struktogramm, StrTabbedPane, XMLLeser, palette/trash setup) for easier maintenance.

Full notes: release-notes/v1.1.4.md.

Changes in 1.1.3 (summary)

• Tabs: close tabs via middle-click, context menu, and Ctrl+W / Cmd+W; clicking the tab header switches diagrams reliably (close “×” is a label, not a button).
• Palette / trash: left-click deletes the selected (highlighted) block with the same confirmation as context-menu Delete; drag-to-trash unchanged.
• Code generator: Java scope and CodeGenRules updates (StruktogrammElementListe, CodeErzeuger, and related).

Full notes: release-notes/v1.1.3.md.

Changes in 1.1.2 (summary)

• Diagram canvas (light theme): styling aligned with VisuStruct-SwiftUI: black block borders (2 px), outer frame inset 16 px, content inset 28 px, selection as blue outline (no blue fill).
• Diagram text: Sans-Serif diagram font (Segoe UI, Helvetica Neue, …), 17 pt; bold control-flow keywords (if, while, …) like Swift; do-while shows do in the left gutter (extra inset); Fallauswahl DE palette label Fallauswahl.
• Left palette: labels follow UI language (structure.palette.*), except preset Java (Standard) (if, while, …).

Full notes: release-notes/v1.1.2.md.

Changes in 1.1.1 (summary)

• About dialog: clearer links for website, GitHub repository, and developer site.
• Palette: Lucide trash icon for the delete area, shown larger.
• File menu: added system Print... support for printing or saving via the OS dialog.

Changes in 1.1 (summary)

• Element editor: first step toward the Swift-style bottom editor panel.

Changes in 1.0.9 (summary)

• Palette: Lucide SVG icons on the element buttons, including split for Branch.
• For loop: multi-line start/condition/increment headers are shown and exported as start; condition; increment.
• Java export: output: statements become System.out.println(...).

Full notes: release-notes/v1.0.9.md.

Changes in 1.0.8 (summary)

• Code generator: JavaScript target (brace syntax like Java, "use strict"; prefix); celanguage 2 = JavaScript in visustruct.properties (with 0 = Java, 1 = Python).
• Generate code dialog: Test in browser (only when JavaScript is selected): confirmation explains valid JS in free lines; opens a temporary HTML preview via the system browser (</script> in user code is escaped).

Full notes: release-notes/v1.0.8.md.

Changes in 1.0.7 (summary)

• Code generator: Delphi/Pascal removed; Python added (3.10+, match / case for multi-way branches); dialog is localized; target language stored in visustruct.properties as celanguage: 0 = Java, 1 = Python.
• Multi-way (Java): default label for the last column is default (not “Else”); string from structure.multiway.defaultCaseLabel (i18n).
• API: XMLLeser load methods renamed ladeXML (fixes the old typo ladeXLM).
• Code: removed unused selection / size-box leftovers from upstream (Struktogramm, StruktogrammElement).
• Build: Maven de.visustruct:visustruct:1.0.7 → artifact visustruct-1.0.7.jar; releases also ship visustruct.jar.

Full notes: release-notes/v1.0.7.md.

Changes in 1.0.6 (summary)

• UI & theme: cleaner menus; light / dark FlatLaf without restart; improved dark-mode readability.
• Languages: Settings → Languages lists 21 languages (same set as VisuStruct-swift, except the Java-keyword pseudo-locale); stored in visustruct.properties (uilanguage). If unset, default follows JVM locale. Regenerate bundles: python3 tools/sync_java_messages_from_swift.py.
• I18n: menu, core confirmation dialogs, JFileChooser labels, context menu, palette (PNG, about, trash, etc.); English is no longer overridden by the OS default locale.
• Structure-chart labels: preset “Java (default)” (and localized equivalents); preview in the settings dialog; palette shows Java keywords on buttons when the Java preset is active.
• Tabs: new diagram tab uses a localized “Untitled”-style title instead of a hard-coded English string.
• Build / build.properties: empty timestamp / revision no longer break startup.
• Build: Maven de.visustruct:visustruct:1.0.6, visustruct-1.0.6.jar, plus visustruct.jar.

Full notes: release-notes/v1.0.6.md.

Changes in 1.0.5 (summary)

• Canvas: colors aligned with VisuStruct light style via CanvasStyle (background, borders, selection, drag preview).
• Save / tabs: tab title and dirty * refer to the correct diagram; saves use UTF-8 with an error dialog on write failure.
• macOS: menu bar inside the window (same as Windows/Linux) so Save works reliably with FlatLaf; FlatLaf 3.7.1; save dialog after tab rename deferred one UI tick.
• Light theme menus: VisuStructTheme improves menu-item readability.

Changes in 1.0.4 (summary)

This release aligns branding and technical identity with VisuStruct. .visustruct / XML project files stay compatible; element types remain numeric in XML.

• Java packages: de.visustruct.* (was de.kekru.struktogrammeditor).
• Maven: de.visustruct:visustruct:1.0.4. Dependents must update groupId, artifactId, and version if needed. Fat JAR: visustruct-1.0.4.jar; workflow also publishes visustruct.jar.
• Settings: default file visustruct.properties; migrates from struktogrammeditor.properties on the next settings save.
• macOS .app: bundle ID and document UTI → de.visustruct.*; you may need to set Open With for .visustruct again. Main: de.visustruct.control.Main.
• Upstream: kekru/struktogrammeditor remains credited (MIT) in README and the about dialog.

Changes in 1.0.3 (summary)

• Build: Maven Wrapper 3.3.4 (script-only), Maven 3.9.9; maven-compiler-plugin 3.14.1, maven-assembly-plugin 3.7.1; compile with -Xlint:deprecation.
• API / Swing: modern modifiers (getModifiersEx, …), generics in JListEasy / FontChooser; JNumberField deprecation cleanups.

Changes in 1.0.2 (summary)

• Code generator: faster buffered output; clearer comments when “diagram text as comments” is enabled.
• New-element text presets in the settings dialog (including English/Java-style placeholders).
• Branding / files: VisuStruct and .visustruct filters and associations.
• Logo and minor UI tweaks.

Platform (1.0.1 and earlier)

• Java 17 target (build and run with JDK 17+).
• FlatLaf light/dark themes; JDOM2; no legacy AppleJavaExtensions.
• Motif look-and-feel removed; Metal and FlatLaf available.
• Current fat JAR name follows pom.xml version (e.g. visustruct-1.2.3.jar).

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Download (no build required)

Install VisuStruct from this repository (the JAR below)—not the legacy kekru/struktogrammeditor project, which remains historical MIT lineage and attribution only.

Students only need a Java 17+ runtime — not Maven.

Latest published build (stable filename):

Download visustruct.jar

Run from the folder that contains the JAR:

java -jar visustruct.jar

On Windows, double-click often works if .jar is associated with Java. If an old JRE (e.g. 8) is the default, you will get Error: A JNI error has occurred — install JDK 17+ and ensure java -version reports 17 or newer (see Troubleshooting below).

All releases: github.com/code4teaching/VisuStruct/releases

Maintainers: To ship a new version, create a GitHub Release with a tag such as vX.Y.Z (one bump per release — not for every local change). Workflow .github/workflows/release-assets.yml builds the JARs and attaches visustruct.jar (stable download URL above). Update pom.xml <version> together with that release.

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Prerequisites

• JDK 17 or newer (to run the JAR; to build, see below)
• Building only: network on first run so Maven can download dependencies

Troubleshooting

Error: A JNI error has occurred, please check your installation and try again

This almost always means the JVM is too old for the JAR. VisuStruct is built for Java 17; an older runtime (e.g. Java 8) cannot load the classes and may show this message before a more specific error.

Fix: Install a JDK or JRE 17+ (e.g. Eclipse Temurin). Then check in a terminal:

java -version

You should see something like openjdk version "17" or "21". If Windows still uses an old java.exe, adjust PATH or call the full path to the new runtime, e.g.:

"C:\Program Files\Eclipse Adoptium\jdk-17...\bin\java.exe" -jar visustruct.jar

UnsupportedClassVersionError

Same cause: upgrade to Java 17+ as above.

Build a runnable JAR

Clone or download the project and open a terminal in the project root.

Windows (PowerShell):

.\mvnw.cmd clean package

Linux or macOS:

chmod +x mvnw
./mvnw clean package

Output (version from pom.xml):

target/visustruct-1.2.3.jar

Run

java -jar target/visustruct-1.2.3.jar

Double-click may work if .jar is associated with Java.

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Contributing

Suggestions and bug reports are welcome via Issues and Pull requests.

Commits and code comments may use English.

UI strings (21 languages)

• Bundles: src/main/resources/de/visustruct/i18n/Messages_*.properties (plus structure.* keys where applicable).

• Source of truth for new keys: add the English string to Messages_en.properties, then extend the Swift↔Java map in the sibling repo VisuStruct-swift/tools/java_swift_i18n_map.json (clone next to this project; see .gitignore).

• Regenerate all locale files from Swift where mapped (tools/README.md):

  python3 tools/sync_java_messages_from_swift.py
  python3 tools/analyze_i18n_gaps.py   # optional: unmapped keys

  Unmapped keys keep the existing bundle text or fall back to English. Desktop-only dialogs may stay English until mapped.

• Menu language is Settings → Languages only (uilanguage in visustruct.properties); do not duplicate a language list in other settings dialogs.

• Open an issue first if keys, didactic wording, or Swift parity are unclear.

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License

MIT — see LICENSE. Copyright to the original codebase remains with Kevin Krummenauer (also stated in LICENSE).

Palette icons are from Lucide (ISC; some icons derived from Feather/MIT). The bundled license text is in src/main/resources/licenses/LUCIDE.txt.

Historical upstream website (attribution)

whiledo.de — Struktogrammeditor — original editor by Kevin Krummenauer (context and license lineage; install VisuStruct from this GitHub project instead).