A simple Java script to verify you're using Java 17+

Looking at Oracle's Java Downloads page, we see the following downloadable LTS versions of Java:

• Java 8
• Java 11
• Java 17
• Java 21

And while you can just run java -version in the Terminal to see the current Java version, sometimes you just want a bit more proof that the script is using a specific version of Java.

To do that, we try to run scripts that only work with specific versions of Java since each version brings with them some new features. See A categorized list of all Java and JVM features since JDK 8 to 21 for examples of added features.

For example, we can run the following script to test whether Text Blocks is included in the local Java version, which was only introduced in JDK 15+.

// dummy.java
public class dummy {
    public static void main(String[] args) {
        System.out.println("""
            Hello, World!
            Hello2
                """);
    }
}

Running javac dummy.java && java dummy should print out the multiline string if you installed JDK 15 and above, and error out if you have Java 14 and below.

This example can be extended by testing other features that only work with specific versions of Java (true for other languages as well).

References

1. StackOverflow: Does Java have support for multiline strings?
2. A categorized list of all Java and JVM features since JDK 8 to 21

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