JDK Versions

jbundle downloads JDK runtimes from Adoptium.

Supported Versions

Version	Type	Status	Notes
11	LTS	Supported
17	LTS	Supported
21	LTS	Default	Recommended
22	STS	Supported
23	STS	Supported
24	STS	Supported
25	LTS	Supported

LTS = Long Term Support (recommended for production) STS = Short Term Support

Usage

# Use default (21)
jbundle build --input . --output ./app

# Specify version
jbundle build --input . --output ./app --java-version 17
jbundle build --input . --output ./app --java-version 25

Or in jbundle.toml:

java_version = 21

Why Not Java 8?

jbundle requires jlink and jdeps, which were introduced in Java 9. These tools are essential for:

• jdeps — Analyzing module dependencies

• jlink — Creating minimal custom runtimes

Java 8 predates the module system (JPMS) and doesn't include these tools.

Recommendations

Production

Use LTS versions (11, 17, 21, 25):

• Longer support lifecycle

• More stable

• Security updates for years

New Projects

Use Java 21 (current LTS):

• Modern features (virtual threads, pattern matching)

• Long-term support until 2029+

• Best balance of features and stability

Specific Features

If you need...	Minimum version
Virtual threads	21
Pattern matching for switch	21
Records	16
Text blocks	15
var keyword	10

AppCDS Compatibility

AppCDS (automatic shared archive) requires JDK 19+. On older JDKs:

• JDK 11-18: Manual CDS configuration (not automatic)

• JDK 19+: Automatic AppCDS via -XX:+AutoCreateSharedArchive

For best startup performance, use JDK 21 or newer.

JDK Download & Cache

JDKs are downloaded from the Adoptium API and cached locally:

~/.jbundle/cache/jdk-21-linux-x64/
~/.jbundle/cache/jdk-21-macos-aarch64/

Downloads are verified with SHA256 checksums. Re-running builds with the same JDK version reuses the cached download.

Adoptium vs Other JDKs

jbundle uses Eclipse Temurin (Adoptium's distribution) because:

• Open source

• Free for commercial use

• Reliable API for automated downloads

• Available for all supported platforms

• TCK certified (passes Java compatibility tests)

Custom JDK distributions (Oracle, Azul, Amazon Corretto) are not currently supported.

Exception: CRaC

For CRaC support (--crac), you need a JDK with CRaC patches. Currently, this means Azul Zulu with CRaC. CRaC support in Adoptium/Temurin is planned but not yet available.