BaseMethodCall.java

import lombok.val;
import org.junit.Assert;
import org.junit.Test;

import java.lang.invoke.*;

/*
Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.

Please don't actually do this... :P
*/
public class ImplLookupTest {
	private MethodHandles.Lookup getImplLookup() throws NoSuchFieldException, IllegalAccessException {
		val field = MethodHandles.Lookup.class.getDeclaredField("IMPL_LOOKUP");
		field.setAccessible(true);
		return (MethodHandles.Lookup) field.get(null);
	}

	@Test
	public void test() throws Throwable {
		val lookup = getImplLookup();
		val baseHandle = lookup.findSpecial(Base.class, "toString",
			MethodType.methodType(String.class),
			Sub.class);
		val objectHandle = lookup.findSpecial(Object.class, "toString",
			MethodType.methodType(String.class),
			// Must use Base.class here for this reference to call Object's toString
			Base.class);
		val sub = new Sub();
		Assert.assertEquals("Sub", sub.toString());
		Assert.assertEquals("Base", baseHandle.invoke(sub));
		Assert.assertEquals(toString(sub), objectHandle.invoke(sub));
	}

	private static String toString(Object o) {
		return o.getClass().getName() + "@" + Integer.toHexString(o.hashCode());
	}

	public class Sub extends Base {
		@Override
		public String toString() {
			return "Sub";
		}
	}

	public class Base {
		@Override
		public String toString() {
			return "Base";
		}
	}
}