This program should not compile, but does:

import java.util.ArrayList;

public class X {
    public static void main(String [] args) {
        Object o = new ArrayList<X>();
// if (o instanceof ArrayList<Integer>) { // illegal generic type for instanceof
// System.out.println("Blah");
// }
        if (o __matches ArrayList<Integer> ai) {
            System.out.println("Blah");
        }
        switch (o) {
            case ArrayList<Integer> ai:
                System.out.println("ArrayList<Integer>");
                break;
            case ArrayList<String> as:
                System.out.println("ArrayList<String>");
                break;
        }
    }
}

and prints:

Blah
ArrayList<Integer>