gistfile1.txt

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;

public class Foo {
    static int normalArray(java.lang.invoke.MethodHandle mh, Object[] args) throws Throwable {
      return (int)mh.invokeWithArguments(args);
    }
    static int polyArray(java.lang.invoke.MethodHandle mh, Object[] args) throws Throwable {
      return (int)mh.invoke(args);
    }
    static int normalDirect(java.lang.invoke.MethodHandle mh, Object[] args) throws Throwable {
      return (int)mh.invokeWithArguments(args[0], args[1]);
    }
    static int polyDirect(java.lang.invoke.MethodHandle mh, Object[] args) throws Throwable {
      return (int)mh.invoke(args[0], args[1]);
    }

    public static int add(int a, int b) { return a+b; }

    public static void main(String[] args) throws Throwable {
      MethodHandle mh = MethodHandles.lookup().unreflect(Foo.class.getMethod("add", Integer.TYPE, Integer.TYPE));
      Object[] ints = { 1, 2 };
      System.out.println(normalDirect(mh, ints));
      System.out.println(normalArray(mh, ints));
      System.out.println(polyDirect(mh, ints));
      System.out.println(polyArray(mh, ints));
    }
}


/*
$ java Foo
3
3
3
Exception in thread "main" java.lang.invoke.WrongMethodTypeException: cannot convert MethodHandle(int,int)int to (Object[])int
        at java.base/java.lang.invoke.MethodHandle.asTypeUncached(MethodHandle.java:884)
        at java.base/java.lang.invoke.MethodHandle.asType(MethodHandle.java:869)
        at java.base/java.lang.invoke.Invokers.checkGenericType(Invokers.java:542)
        at Foo.polyArray(Foo.java:9)
        at Foo.main(Foo.java:26)
*/