How to execute a java script with jshell?

user_367796 0
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Given that Java 9 is upon us and we can finally have a java REPL with jshell I was hoping there was a way to add a shebang to a script and have jshell interpret it.

I tried creating test.jsh:

#!/usr/bin/env jshell -s
System.out.println("Hello World")
/exit

However that gives:

⚡ ./test.jsh
|  Error:
|  illegal character: '#'
|  #!/usr/bin/env jshell -s
|  ^
|  Error:
|  illegal start of expression
|  #!/usr/bin/env jshell -s
|    ^
Hello World

It turns out there is an enhancement request for this in OpenJDK https://bugs.openjdk.java.net/browse/JDK-8167440.

Is there any other way to do this?

jshell java-9 shebang java
4 Answers
user_6356210

The below works too; put it into a someScript.jsh file and run it with ./someScript.jsh. All arguments received by someScript.jsh will go to String[] args.

#!/home/gigi/.sdkman/candidates/java/current/bin/java --source 11

import java.util.Arrays;
import ro.go.adrhc.*; // example of using your classes, e.g. App below

public class X {
    public static void main(String[] args) {
        // do whatever you want here, e.g.:
        // System.out.println("Hello World");
        // or
        // use a class:
        // App.main(args);
        // e.g. from ro.go.adrhc package, by running:
        // CLASSPATH="/path-to-ro.go.adrhc-classes" ./someScript.jsh 
    }
}

The usage of the wrapping class, here X, is a mandatory trick for this to work.
Inspired by https://blog.codefx.org/java/scripting-java-shebang/.

user_46812650
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