Switch Statement

The switch statement has almost identical functionality to an if-else block, but looks much cleaner.

switch(expression) {
  case value:
    // run some code
    break; //optional, but typically used
  case value:
    // run some code
    break;
  default:
    // run some code
}

The syntax can seem weird at first, but let's break it down piece by piece.

switch and case are reserved words, and are always there. You can have as many cases as you want.

expression is a variable or expression that will be checked by your cases.

value is a unique value for each case. It can be any data type, (e.g. "Hello" or 12 are both fine), but are usually the same data type in a case block.

break is optional, but you should almost always include it. If expression matches a case, the code in the appropriate case will run. If break is present, it's on the last line before the next case. It will break out of the switch block. If break is not present, rather than breaking out of the block, the next case will run (until the end, or until a break is reached). Usually, you don't want any code to run except a single case, but there are exceptions.

default runs if no cases are matched. Think of it as equivalent to else.

tip

A key difference between if-else and switch is that if-else can take more complex conditions, while switch can only take specific cases.

For example, you can use if (myVar >= 3 && myVar <= 100) in an if/else block.

But, you cannot use (myVar >= 3 && myVar <= 100) in a switch block.

To reiterate, a case label can be:

a string literal (e.g. "Hello")
a constant expression, such as a character ('E'), integer (int, short, etc.)
these may either be typed directly as a case label, or they may be a variable

Let's compare an if-else block with an equivalent switch block. Both will do the exact same thing.

public class Learn {
    public static void main(String[] args) {
        String car = "BMW";

        if (car.equals("Honda")) {
            System.out.println("Nice Honda!");
        } else if (car.equals("BMW")) {
            System.out.println("Cool BMW!");
        } else if (car.equals("Ford")) {
            System.out.println("That's a chonky Ford!");
        } else {
            System.out.println("What kind of car do you drive?");
        }

        // Now, let's rework the above code as a switch statement

        switch (car) {
            case "Honda":
                System.out.println("Nice Honda!");
                break;
            case "BMW":
                System.out.println("Cool BMW!");
                break;
            case "Ford":
                System.out.println("That's a chonky Ford!");
                break;
            default:
                System.out.println("What kind of car do you drive?");
        }
    }
}

Cool BMW!
Cool BMW!

Awesome, they do the same thing! In order to cement your understanding, try two things:

change the value of car to another make on the list, or another make that's not on the list.
Remove all break;s from the switch block. What happens? Do you understand why you should have break as the last line in each case?

In summary, switch is essentially a cleaner looking version of if-else. It has it's limitations, but overall, we prefer to use it when comparing specific values rather than complex conditionals.

Switch Example

If you're a college/university student, chances are you've been given an assignment where you have to create a mock program for a bank, store, etc. that has a menu of options.

A menu of options is where the switch statement excels. We recommend you use it to create clean, readable decision code that fits these requirements:

the decisions are simple words, numbers, or other choices (e.g. 1, 2, 3, etc.)
there are a lot of options, and giant if-else blocks would look messy (you can have short switch statements too. mainly focus on the first requirement above)

import java.util.Scanner;

public class Learn {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        System.out.println("$$$ Welcome to the Open Mastery Bank $$$");
        System.out.println("Please select your option: ");
        System.out.println("1: Deposit");
        System.out.println("2: Withdraw");
        System.out.println("3: See Balance");
        System.out.println("4: Exit");
        System.out.print("> ");
        int choice = in.nextInt();

        switch (choice) {
            case 1:
                // do something
                break;
            case 2:
                // do something
                break;
            case 3:
                // do something
                break;
            case 4:
                System.out.println("Exiting...");
                // do something
                break;
            default:
                System.out.println("Invalid option");
        }
    }
}

Switch Statement

Switch Example​

Switch Example