Using Java in Jobs¶

Overview¶

If your code uses Java via a .jar file, it is easy to bring along your own copy of the Java Development Kit (JDK) which allows you to run your .jar file anywhere on the Open Science Pool.

Steps to Use Java in Jobs¶

Get a copy of Java/JDK. You can access the the Java Development Kit (JDK) from the JDK website. First select the link to the JDK that is listed as "Ready for Use" and then download the Linux/x64 version of the tar.gz file using a Unix command such as wget from your /home directory. For example,
```
$ wget https://download.java.net/java/GA/jdk17.0.1/2a2082e5a09d4267845be086888add4f/12/GPL/openjdk-17.0.1_linux-x64_bin.tar.gz
```

The downloaded file should end up in your home directory on the OSPool access point.

Include Java in Input Files. Add the downloaded tar file to the transfer_input_files line of your submit file, along with the .jar file and any other input files the job needs:
```
transfer_input_files = openjdk-17.0.1_linux-x64_bin.tar.gz, program.jar, other_input
```
Setup Java inside the job. Write a script that unpacks the JDK tar file, sets the environment to find the java software, and then runs your program. This script will be your job\'s executable. See this example for what the script should look like:
```
#!/bin/bash

# unzip the JDK
tar -xzf openjdk-17.0.1_linux-x64_bin.tar.gz
# Add the unzipped JDK folder to the environment
export PATH=$PWD/jdk-17.0.1/bin:$PATH
export JAVA_HOME=$PWD/jdk-17.0.1

# run your .jar file
java -jar program.jar
```
Note that the exact name of the unzipped JDK folder and the JDK tar.gz file will vary depending on the version you downloaded. You should unzip the JDK tar.gz file in your home directory to find out the correct directory name to add to the script.