Java switch Statement

The switch statement allows us to execute a block of code among many alternatives.

The syntax of the switch statement in Java is:

switch (expression) {

  case value1:
    // code
    break;

  case value2:
    // code
    break;

  ...
  ...

  default:
    // default statements
  }

How does the switch-case statement work?

The expression is evaluated once and compared with the values of each case.

• If expression matches with value1, the code of case value1 are executed. Similarly, the code of case value2 is executed if expression matches with value2.
• If there is no match, the code of the default case is executed.

Example: Java switch Statement

Input

// Java Program to check the size
// using the switch...case statement

class Main {
  public static void main(String[] args) {

    int number = 44;
    String size;

    // switch statement to check size
    switch (number) {

      case 29:
        size = "Small";
        break;

      case 42:
        size = "Medium";
        break;

      // match the value of week
      case 44:
        size = "Large";
        break;

      case 48:
        size = "Extra Large";
        break;

      default:
        size = "Unknown";
        break;

    }
    System.out.println("Size: " + size);
  }
}

Output:

Size: Large

In the above example, we have used the switch statement to find the size. Here, we have a variable number. The variable is compared with the value of each case statement.

Since the value matches with 44, the code of case 44 is executed.

size = "Large";
break;

Here, the size variable is assigned with the value Large.

Flowchart of switch Statement

break statement in Java switch...case

Notice that we have been using break in each case block.

 ...
case 29:
  size = "Small";
  break;
...

The break statement is used to terminate the switch-case statement. If break is not used, all the cases after the matching case are also executed. For example,

Input

class Main {
  public static void main(String[] args) {

    int expression = 2;

    // switch statement to check size
    switch (expression) {
      case 1:
        System.out.println("Case 1");

        // matching case
      case 2:
        System.out.println("Case 2");

      case 3:
        System.out.println("Case 3");

      default:
        System.out.println("Default case");
    }
  }
}

Output

Case 2
Case 3
Default case

In the above example, expression matches with case 2. Here, we haven’t used the break statement after each case.

Hence, all the cases after case 2 are also executed.

This is why the break statement is needed to terminate the switch-case statement after the matching case. To learn more, visit Java break Statement.

default case in Java switch-case

The switch statement also includes an optional default case. It is executed when the expression doesn’t match any of the cases. For example,

Input

class Main {
  public static void main(String[] args) {

    int expression = 9;

    switch(expression) {

      case 2:
        System.out.println("Small Size");
        break;

      case 3:
        System.out.println("Large Size");
        break;

      // default case
      default:
        System.out.println("Unknown Size");
    }
  }
}

Output

Unknown Size

In the above example, we have created a switch-case statement. Here, the value of expression doesn’t match with any of the cases.

Hence, the code inside the default case is executed.

default:
  System.out.println("Unknown Size);