README.md

Hello Graal Java Example

This is a "Hello Graal" Java example for GraalVM. The structure of the Hello package is like this:

.
| src
|   `--com/
|      `-- hello
|          `-- Graal.java
|-- LICENSE
|-- .gitignore
|-- manifest.txt
`-- README.md

Download and install the latest GraalVM JDK using SDKMAN!.
```
sdk install java 21.0.1-graal
```
Download or clone GraalVM demos repository and navigate into the hello-graal directory:
```
git clone https://github.com/graalvm/graalvm-demos
```
```
cd graalvm-demos/hello-graal
```

Compile the application running the follow command:
```
$JAVA_HOME/bin/javac -d build src/com/hello/Graal.java
```
This generates the Graal.class file into build/com/hello directory.
Run the application from a class file:
```
$JAVA_HOME/bin/java -cp ./build com.hello.Graal
```
It outputs the message "hello graal".

Create a JAR for the application, running the follow command:

$JAVA_HOME/bin/jar cfvm Hello.jar manifest.txt -C build .
jar tf Hello.jar

The output will be:

META-INF/
META-INF/MANIFEST.MF
com/
com/hello/
com/hello/Graal.class

Run the JAR file:
```
$JAVA_HOME/bin/java -jar Hello.jar
```
It outputs the message "hello graal".

Create a native executable of a JAR file:
```
$JAVA_HOME/bin/native-image -jar Hello.jar
```
The executable called ./Hello will be created in the working directory.
Execute it:
```
./hello
```
It outputs the message "hello graal". To check the filesize of the executable image, run: ls -lh Hello.