MethodHandle#invokeExact() invocation example

MethodHandleInvokeExactSample.java

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

class Base {
    int x = 13;
}

class Derived extends Base {
    public long m;
}

public class TestMH {
    public static void main(String[] args) throws Throwable {
        MethodHandle mh = MethodHandles.lookup().findGetter(Base.class, "x", int.class);

        Derived obj = new Derived();

        // mh.invokeExact(obj); => throws WrongMethodTypeException:expected(Base)int but found (Derived)void

        // mh.invokeExact((Base) obj); => throws WrongMethodTypeException:expected(Base)int but found (Base)void

        int value = (int) mh.invokeExact((Base) obj);
    }
}