Java Nashorn - ClassNotFoundException - Java.type()

• Nashorn uses the thread context loader found at the time of engine creation to find Java classes from Java.type API.

• Nashorn also uses another loader if you use "-classpath" nashorn command line option. Nashorn tries to load classes using a fresh loader created during engine creation initialized with that classpath specified. Note that nashorn command line options can be passed via "nashorn.args" Java System property. So, if you specific -Dnashorn.args="-classpath your_path" elsewhere (say, in your config), then Nashorn can access classes from that your_path specified.

If cannot pass Nashorn engine options via System property [or via command line in the case "jjs" tool use], you can set thread context loader to be appropriate loader as suggested by an earlier answer.

If that is not desired because of other application dependencies, you get java.lang.Class object of the desired class and expose the same as variable to the script (from your Java code, you could get Class object and call ScriptEngine.put method). The script then can access "static" property on that to get 'type' object. With type object, usual "new", static method calls etc. work as expected.

Example:

import javax.script.*;

public class Main {
   public static void main(String[] args) throws Exception {
       ScriptEngineManager m = new ScriptEngineManager();
       ScriptEngine e = m.getEngineByName("nashorn");
       e.put("Vec", java.util.Vector.class); // replace it with any Class object
       e.eval("var T = Vec.static; var obj = new T()"); // create new Vector
       e.eval("print(obj.getClass())");
   }
}