native-hello-module

GraalVM Demos: Building a HelloWorld Java Module into a Native Executable

This repository contains the code for a demo application for GraalVM.

Prerequisites

• GraalVM
• Native Image
• Maven

Preparation

1. Download GraalVM, unzip the archive, export the GraalVM home directory as the $GRAALVM_HOME and add $GRAALVM_HOME/bin to the PATH environment variable.

On Linux:

export GRAALVM_HOME=/home/${current_user}/path/to/graalvm
export PATH=$GRAALVM_HOME/bin:$PATH

On macOS:

export GRAALVM_HOME=/Users/${current_user}/path/to/graalvm/Contents/Home
export PATH=$GRAALVM_HOME/bin:$PATH

On Windows:

setx /M GRAALVM_HOME "C:\Progra~1\Java\<graalvm>"
setx /M PATH "C:\Progra~1\Java\<graalvm>\bin;%PATH%"

2. Install Native Image by running:

gu install native-image

For compilation, the native-image tool depends on the local toolchain. Please make sure that glibc-devel, zlib-devel (header files for the C library and zlib), and gcc are available on your system. Some Linux distributions may additionally require libstdc++-static. See Prerequisites for Native Image.

3. Download or clone the repository and navigate into the native-hello-module directory:

git clone https://github.com/graalvm/graalvm-demos
cd graalvm-demos/native-hello-module

Build the Application

Before running this example, you need to build the application:

$ mvn package

This creates a JAR file with all dependencies embedded: target/HelloModule-1.0-SNAPSHOT.jar

Run the Application

The following modularized Java Hello World example

├── hello
│   └── Main.java
│       > package hello;
│       > 
│       > public class Main {
│       >     public static void main(String[] args) {
│       >         System.out.println("Hello from Java Module: "
│       >             + Main.class.getModule().getName());
│       >     }
│       > }
│
└── module-info.java
    > module HelloModule {
    >     exports hello;
    > }

can be executed via Java using the following command:

$ java --module-path target/HelloModule-1.0-SNAPSHOT.jar --module HelloModule
Hello from Java Module: HelloModule

With GraalVM you can now build Java modules into native executables, using the following syntax:

$ native-image --module-path target/HelloModule-1.0-SNAPSHOT.jar --module HelloModule

[hellomodule:10847]    classlist:     513.59 ms,  0.96 GB
[hellomodule:10847]        (cap):     386.65 ms,  0.96 GB
....
[hellomodule:10847]        image:     968.93 ms,  4.85 GB
[hellomodule:10847]        write:     201.81 ms,  4.85 GB
[hellomodule:10847]      [total]:  19,216.19 ms,  4.85 GB

It builds the modular Java app into a native executable that can be executed with:

$ ./hellomodule 
Hello from Java Module: HelloModule