Pass js array to a Java method pointer
qiyi
bphanzhu at gmail.com
Tue May 16 18:03:40 UTC 2017
Hi, all, I'am trying to add a function to nashorn engine's bindings, and
these methods I have tried:
public class MyFunction implements Function<Object[], Object> {
@Override
public Object apply(Object[] objects) {
return Arrays.toString(objects);
}
public Object f2(Object[] objects) {
return Arrays.toString(objects);
}
public Object f3(Object object) {
return object;
}
public Object f4(Object[] objects) {
return Arrays.toString(objects);
}
public static void main(String[] args) throws ScriptException {
MyFunction myFunction = new MyFunction();
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine nashorn = manager.getEngineByName("nashorn");
Bindings bindings = nashorn.getBindings(ScriptContext.ENGINE_SCOPE);
bindings.put("f1", myFunction);
bindings.put("f", myFunction);
bindings.put("f3", (Function<Object, Object>) myFunction::f3);
bindings.put("f4", (Function<Object[], Object>) myFunction::f4);
System.out.println(nashorn.eval("f1([1,2])")); // run ok, ret: [1,2]
System.out.println(nashorn.eval("f.f2([1,2])")); // run ok, ret: [1, 2]
System.out.println(nashorn.eval("f3(\"f3\")")); // run ok, ret: f3
System.out.println(nashorn.eval("f4([1,2])")); // run fail,
ClassCastException: ScriptObjectMirror cannot be cast to
[Ljava.lang.Object
}
}
The problem is the f4 function, this method pointer receive Object[]
parameter and nashorn will throw exception with ClassCastException.
But why nashorn could not infer the parameter type and auto convert
the js array to java array, will it be a bug of nashorn
More information about the nashorn-dev
mailing list