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@synapticloop synapticloop released this 25 Oct 06:10
0.16.2-beta
5bb711c

snug 0.16.2 — beta

build it. brand it. share it.

Snug turns a runnable Java application into a native Windows x64 .exe that people can double-click.

This is the first public release of snug, published as a beta. It is usable today, but the command-line surface is still settling and a few sharp edges are documented below. Read the Beta caveats before you build anything you intend to distribute widely.

Read the extensive documentation synapticloop.github.io/snug/

What snug is

You have a Java application that runs as a JAR. Snug wraps that JAR — and a small native launcher — into a single Windows executable:

MyApp.jar
   │
   ▼
 snug MyApp.jar
   │
   ▼
MyApp.exe  ──►  extracts to a per-user cache
               ──►  finds a compatible Java runtime
               ──►  calls into the JVM through JNI
               ──►  runs your application

The result behaves like any other Windows program:

  • It has your name. The process shows up in Task Manager as MyApp.exe, not javaw.exe.
  • It has your icon. PNG or ICO, stamped into the executable as a real Windows resource.
  • It has your details. Name, company, version, description and copyright land in the Windows file properties, where Explorer and Task Manager read them.
  • It can have a splash screen. A PNG shown while the JVM starts.

snug does not bundle a JVM

The executable carries your application, not a Java runtime. On launch, snug looks for a compatible Java install in the usual places — JAVA_HOME, JDK_HOME, PATH, the Windows registry, and common install locations — and requires Java 25 or newer by default (adjustable with --min-java).

If no compatible runtime is found, snug can offer to download Eclipse Temurin for the user, verifying the archive against its published SHA-256 before installing it. An old JDK counts as "no compatible runtime", so a machine with Java 11 installed gets the same offer as a machine with no Java at all.

Runtime behaviour worth knowing

  • The JAR is extracted once into a per-user cache (%LOCALAPPDATA%\snug\<company>\<app>\<sha256>\) and reused on later launches.
  • Old cache entries are swept automatically — recently used builds are kept, stale ones are removed.
  • Single instance is the default. A second launch raises the already-running window and exits, instead of starting a competing copy. Opt out with --allow-multiple-instances.
  • Runtime messages are localisable, and the launcher's language follows the user's Windows UI language.

What's in the download

File What it is
snug-0.16.2-windows-x86_64.zip The release bundle. Unpacks to a snug\ folder containing the three tools below.
snug-javafx-demo-windows.jar A runnable JavaFX demo application, so you can try snug without writing any Java.

Inside snug\:

Tool What it does
snug.exe The builder. The command-line tool that turns a JAR into an .exe. This is the one you want.
Snug Quick Build.exe The beginner shim. Drop a JAR (or a folder of JARs) onto it and it builds the .exe for you, then reports the result. Must stay in the same folder as snug.exe.
snug_preview.exe The dialog previewer. Renders every launcher dialog so a copy or translation change can be judged by eye. A development tool — you do not need it to build applications.

Try it in about a minute

# 1. Unzip snug-0.16.2-windows-x86_64.zip
# 2. Put the demo JAR next to snug.exe, then:
.\snug.exe .\snug-javafx-demo-windows.jar

# 3. Double-click the snug-javafx-demo-windows.exe it just produced

Your own application is the same command with your JAR:

.\snug.exe .\MyApp.jar

By default the output .exe is written next to the input JAR.

Make it yours

.\snug.exe .\MyApp.jar `
  --name "My Application" `
  --company "My Company" `
  --version 1.2.3 `
  --icon .\icon.png `
  --splash .\splash.png

Useful flags:

Flag Purpose
-o, --output Where to write the .exe.
--name, --company Display name and publisher.
--version, --description, --copyright Windows file properties.
--icon Application icon (PNG or ICO).
--splash, --splash-ms, --splash-max Splash screen and its timing.
--manifest An arbitrary Windows application manifest (XML).
--min-java Lowest acceptable Java major version. Default 25.
--main-class Override the entry point when the manifest is ambiguous.
--jvm-arg Pass a JVM option. Repeatable.
--download-jdk off, auto (default) or force — controls the Temurin offer.
--allow-multiple-instances Permit more than one copy to run.
--localisation A translation file, or a directory of them.
--dry-run Validate and report without writing anything.

For repeatable builds, snug.options files supply the same settings; run snug.exe --init-options for a starter file. snug.exe --help is the authoritative reference for your build.

Localisation

Launcher messages ship with an English baseline and can be translated. --init-localisations --init-localisations-tag de writes a starter file; --list-tokens prints the placeholder contract. Snug warns at build time if a bundle's keys or placeholders do not match the English baseline.

What snug is not

This matters as much as the feature list, so it is stated plainly:

  • It is not an installer. snug does not create Start menu entries, install into Program Files, or write an uninstaller. The .exe is your application. Delete it and the application is gone — although cached files and any downloaded Java runtime may remain behind.
  • It is not a JVM distribution. snug does not ship a runtime; it finds one or offers to download one.
  • It does not update your application. There is no auto-update mechanism. You decide how new versions reach users.
  • It does not sign your executable. These builds are unsigned, so Windows SmartScreen will likely warn on first run, and some organisations block unsigned executables outright.
  • It is not a jpackage replacement. snug produces an application executable; it is not an installer toolchain, a dependency resolver, or a native-image compiler.

Beta caveats

Known limitations in this build:

  • Windows x64 only. macOS and Linux code exists in the repository but is experimental and is not part of this release.
  • The CLI surface is still moving. Flags have been renamed recently — --localization is now --localisation, --download-jdk now requires a value, and --company falls back to your application name when omitted. Expect further adjustment before 1.0; now is a good time to tell us what should look different.
  • Java 25 is the default floor. If your application targets an older Java, either lower --min-java or rebuild your fat JAR against Java 25.
  • Single instance is enforced by default. Identity is --company + --name, not the executable path, so two differently-branded builds run side by side — but two copies of the same build will not.
  • Unsigned binaries. Expect a SmartScreen prompt on first run.
  • Single-instance detection and the launcher are Windows-only. macOS support is detection-only and has no splash, no download dialogs, and no error dialogs.
  • The cache is per-user, under %LOCALAPPDATA%\snug\. A portable "runs anywhere from a USB stick" deployment is not a supported scenario.

Try it and tell us what breaks

snug is developed in the open and the whole implementation is on GitHub.

Beta releases are for shaking out exactly the problems listed above. If something does not work — on your Java version, your Windows build, or your application — that is the most valuable thing you can report right now.

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