Java returns cannont invoke ScriptEngine error

Question

I am running Java's ScriptEngine class to run to some code. I use IntelliJ with maven dependencies when I run the code it says

Cannot invoke "javax.script.ScriptEngine.eval(String)" because "this.engine" is null
    at Run.Evaluater.<init>(Evaluater.java:19)

the code at line being the following

engine.put("event", event);
engine.put("content", message);

This is how I initiated the ScriptEngone

    public ScriptEngineManager man = new ScriptEngineManager();
    public ScriptEngine engine = man.getEngineByName("nashorn");

JDK 15 or later? It's gone. https://bugs.openjdk.java.net/browse/JDK-8236933 — Tom Hawtin - tackline, Nov 07 '20 at 11:36
Even then it says this.engine might be null. That's why I sent the place where instantiated the variable, so someone would be able to say if instantiation was wrong — abhishekmohan20xx, Nov 07 '20 at 16:00
From https://stackoverflow.com/questions/25332640/getenginebynamenashorn-returns-null it looks like the no-args `ScriptEngineManager` constructor uses `Thread.currentThread().getContextClassLoader()`. Specifying `null` as an argument bypasses anything weird the tccl might be doing, but still depends upon nashorn being present. — Tom Hawtin - tackline, Nov 07 '20 at 16:47
(As a rule, anything thread local is a bad idea. Inheritably thread local, even more so.) — Tom Hawtin - tackline, Nov 07 '20 at 17:04

score 1 · Answer 1 · answered Sep 06 '21 at 06:12

1

This error was encountered when a project was cloned from the code cloud when it was running. This part of the content is about the loading of the verification code. I did not understand the reason but it was a version problem. Change the JDK version from The problem is solved when 13 is reduced to 8.

answered Sep 06 '21 at 06:12

Gayan Chinthaka

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Change to openjdk 8, worked for me. Thanks! – JRichardsz Jan 31 '23 at 05:27

Java returns cannont invoke ScriptEngine error

1 Answers1