How to use instanceof in Java?

Question

So I have an arrayList with rooms and im getting the user to put in the room they are looking for, im capturing this as a string and then trying to use instanceOf to match it up with the names of the java classes but cant do this due to comparing a string to a java class.

Also I am capturing there answer in a switch statement to make sure the classes are perfectly spelt and what not. just not sure how to reach in the arrayList and pull out the class they are looking for.

public static void serachRooms(ArrayList<Room> rooms) {
        int option = 0;
        String temp = "";
        boolean flag = false;
        do {
            System.out.println("please Enter What room Type you would like:"
                    + "\nNormal Room = 1"
                    + "\nComputer Room = 2"
                    + "\nBiology Lab = 3"
                    + "\nBoard Room = 4"
                    + "\nYou must choose one!");
            option = input.nextInt();
            if (option == 1 || option == 2 || option == 3 || option == 4) {
                flag = true;
            }
        } while (!flag);
        switch (option) {
            case 1:
                temp = "BiologyLab";
                break;
            case 2:
                temp = "BoardRoom";
                break;
            case 3:
                temp = "ComputerRoom";
                break;
            case 4:
                temp = "Room";
                break;
        }
        for (Room room : rooms) {
            if (temp instanceof BiologyLab) {

            }
        }
    }

`temp` is a `String`; don't use `instanceof`. Also, it isn't clear why you need `temp`. — Elliott Frisch, Mar 28 '19 at 00:11
You may want to review what `instanceof` is actually. Look at https://stackoverflow.com/questions/7313559/what-is-the-instanceof-operator-used-for-in-java or similar. — PM 77-1, Mar 28 '19 at 00:13

score 1 · Answer 1 · answered Mar 28 '19 at 00:27

instanceof is something pretty special that has to do with types and inheritance. Check out the Java documentation.

For your case, you want to compare the String temp to the String "BiologyLab". Just use

if ("BiologyLab".equals(temp)) { 
    ...
}

and check out How To Compare Strings In Java for more information.

How to use instanceof in Java?

1 Answers1