CODEWITHSUNDEEP
javajava-6java-scripting-engine
Ksenia
Ksenia

Reputation: 3753

ScriptEngine with name "nashorn" is null

I'm trying to create ScriptEngine with name "nashorn":

ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("nashorn");
if (engine == null) {
     System.out.println("engine == null");
}

But I always get 

engine == null

Why is this happening? The docs say:

The Nashorn engine is the default ECMAScript (JavaScript) engine bundled with the Java SE Development Kit (JDK).

It means that the Nashorn engine is the default engine and must be present in JDK, don't it?

Upvotes: 1

Views: 3340

Answers (2)

dulon
dulon

Reputation: 754

I had the same problem despite actually using Java 8.

To get it working, replace

ScriptEngineManager manager = new ScriptEngineManager();

With the following:

ScriptEngineManager manager = new ScriptEngineManager(null);

The reason the latter worked is mentioned in the following javadoc:

This constructor loads the implementations of ScriptEngineFactory visible to the given ClassLoader using the service provider mechanism.

If loader is null, the script engine factories that are bundled with the platform and that are in the usual extension directories (installed extensions) are loaded.

Upvotes: 0

SubOptimal
SubOptimal

Reputation: 22973

Here a small snippet to list all supported engines

public class Script {
    public static void main(String[] args) throws ScriptException {
        new ScriptEngineManager().getEngineByName("js")
           .eval("print('Hello from Java\\n');");
        for (ScriptEngineFactory se : new ScriptEngineManager().getEngineFactories()) {
            System.out.println("se = " + se.getEngineName());
            System.out.println("se = " + se.getEngineVersion());
            System.out.println("se = " + se.getLanguageName());
            System.out.println("se = " + se.getLanguageVersion());
            System.out.println("se = " + se.getNames());
        }
    }
}

Java 6 (1.6.0_43)

Hello from Java
se = Mozilla Rhino
se = 1.6 release 2
se = ECMAScript
se = 1.6
se = [js, rhino, JavaScript, javascript, ECMAScript, ecmascript]

Java 7 (1.7.0_40)

Hello from Java                                                  
se = Mozilla Rhino                                               
se = 1.7 release 3 PRERELEASE                                    
se = ECMAScript                                                  
se = 1.8                                                         
se = [js, rhino, JavaScript, javascript, ECMAScript, ecmascript]

Java 8 (1.8.0_74)

Hello from Java

se = Oracle Nashorn
se = 1.8.0_74
se = ECMAScript
se = ECMA - 262 Edition 5.1
se = [nashorn, Nashorn, js, JS, JavaScript, javascript, ECMAScript, ecmascript]

Upvotes: 4

Related Questions