Java Switch

Java Switch Statement

Instead of writing long if..else if..else statements, you can use the switch statement. The switch statement selects one of many code blocks to be executed.

How It Works

The switch expression is evaluated once. The value of the expression is compared with the values of each case. If there is a match, the associated block of code is executed.

The break and default keywords are optional, and will be described later in this chapter.

public class Main {
  public static void main(String[] args) {
    int day = 4;
    switch (day) {
      case 1:
        System.out.println("Monday");
        break;
      case 2:
        System.out.println("Tuesday");
        break;
      case 3:
        System.out.println("Wednesday");
        break;
      case 4:
        System.out.println("Thursday");
        break;
      case 5:
        System.out.println("Friday");
        break;
      case 6:
        System.out.println("Saturday");
        break;
      case 7:
        System.out.println("Sunday");
        break;
    }
    // Outputs "Thursday" (day 4)
  }
}

The break Keyword

When Java reaches a break keyword, it breaks out of the switch block. This will stop the execution of more code and case testing inside the block.

If you omit the break, execution will "fall through" to the next case and execute its code block regardless of whether the case matches.

The default Keyword

The default keyword specifies some code to run if there is no case match. If no case matches the switch expression, the default block is executed.

int day = 9;
switch (day) {
  case 6:
    System.out.println("Today is Saturday");
    break;
  case 7:
    System.out.println("Today is Sunday");
    break;
  default:
    System.out.println("Looking forward to the Weekend");
}
// Outputs "Looking forward to the Weekend"