import java.lang.invoke.VarHandle;
import java.lang.invoke.MethodHandles;

public class Example {
    static class Outer {
        Object f;
    }

    static final VarHandle fVarHandle;
    static {
        MethodHandles.Lookup l = MethodHandles.lookup();
        try {
            fVarHandle = l.findVarHandle(Outer.class, "f", Object.class);
        } catch (Exception e) {
            throw new Error(e);
        }
    }

    static boolean testCompareAndSwap(Outer o, Object oldVal, Object newVal) {
        return fVarHandle.compareAndSet(o, oldVal, newVal);
    }

    public static void main(String[] args) {
        for (int i = 0; i < 10_000; i++) {
            Outer o = new Outer();
            Object oldVal = new Object();
            o.f = oldVal;
            Object newVal = new Object();
            testCompareAndSwap(o, oldVal, newVal);
        }
    }
}