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
  }

1. How does the switch-case statement work?

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

• If expression matches value1, the code of case value1 is executed.
• If there is no match, the code of the default case is executed.

Example: Java switch Statement

// Java Program to check the size
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

2. 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.

Fall-Through: If you omit the break, execution will continue to the next case (fall-through).

int day = 2;
switch (day) {
  case 1:
  case 2:
  case 3:
  case 4:
  case 5:
    System.out.println("Weekday");
    break;
  case 6:
  case 7:
    System.out.println("Weekend");
    break;
}

3. The default Keyword

The default keyword specifies some code to run if there is no case match.

int day = 4;
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");
}

4. Enhanced Switch (Java 12+)

Java 12 introduced a new switch expression that is more concise and less error-prone. It uses the -> arrow syntax and doesn't require break statements.

int day = 3;
String dayName = switch (day) {
    case 1 -> "Monday";
    case 2 -> "Tuesday";
    case 3 -> "Wednesday";
    case 4 -> "Thursday";
    case 5 -> "Friday";
    case 6 -> "Saturday";
    case 7 -> "Sunday";
    default -> "Invalid day";
};
System.out.println(dayName);

Benefits:

• No Fall-Through: You don't need break.
• Returns a Value: Can be used as an expression.
• Concise: Less boilerplate code.

Key Takeaways

• Efficiency: switch is cleaner than many if-else-if blocks when checking one variable.
• Case: Defines a value to match.
• Break: Exits the switch block.
• Default: Runs if no cases match (like else).
• Enhanced Switch: Use -> for cleaner code in modern Java.

Common Pitfalls

[!WARNING] Fall-Through: Forgetting break causes the code to "fall through" and execute the next case's code too.

[!WARNING] Supported Types: You can't switch on long, float, double, or boolean. Only byte, short, char, int, String, and enums are allowed.

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