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.

Note: The working of the switch-case statement is similar to the Java if...else...if ladder. However, the syntax of the switch statement is cleaner and much easier to read and write.

Example: Java switch Statement

// 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.

Recommended Reading: Create a Simple Calculator Using the Java switch Statement

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,

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,

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);