Switch Statement instead of if statements

Question

i created a class with switch statement that prints out the name of a polygon based on the number of sides chosen by the user. The problem I cant figure out is how to do this when a side is less than 3 and more than 12. I would have rather liked to have used if statements but I cant for this part. Since I can use a case: for every number over 12 such as case 13:, case 14: etc.. how can I do this?

import java.util.Scanner;
public class Lab13 {
    public static void main(String[] args) {
        int sides = 0;
        Scanner scan = new Scanner(System. in );
        System.out.println("Please enter the number of sides of your Polygon");
        sides = scan.nextInt();
        String polygonname = "";
        switch (sides) {
        case 3:
            polygonname = polygonname + "triangle";
            break;
        case 4:
            polygonname = polygonname + "square";
            break;
        case 5:
            polygonname = polygonname + "pentagon";
            break;
        case 6:
            polygonname = polygonname + "hexagon";
            break;
        case 7:
            polygonname = polygonname + "heptagon";
            break;
        case 8:
            polygonname = polygonname + "octagon";
            break;
        case 9:
            polygonname = polygonname + "nonagon";
            break;
        case 10:
            polygonname = polygonname + "decagon";
            break;
        case 12:
            polygonname = polygonname + "dodecagon";
            break;
        }
        System.out.print("A polygon with " + sides + " sides is called a " + polygonname + ".");
    }
}

Answer 1

You should accept Oscar's answer. I only added mine to make a point about final being a good practice when doing switch/case. Java's Switch statement is unfortunately not expression based nor exhaustive. You can fix that by using final variables and the compiler will get mad if you don't handle a case.

    final String polygonname;

    switch (sides) {
    case 3:
        polygonname = "triangle";
        break;
    case 4:
        polygonname = "square";
        break;
    // Other cases....
    case 10:
        polygonname = "decagon";
        break;
    case 12:
        polygonname = "dodecagon";
        break;
    default:
        polygonname = "n-gon";

    }

Answer 2

Use default: at the end of the switch, that'll take care of all the other cases, it's like the final else in an if / else if / else if statement. Write it like this:

switch(sides) {

case 3:
polygonname=polygonname+"triangle";
break;

// ...

default:
polygonname=polygonname+"unknown";
break;

}