Java Switch Statement: Syntax, Examples, and Key Points

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Question:

Introduce Java Switch and give examples

Answer:

The switch statement in Java is a control flow statement that allows you to execute one block of code among many based on the value of a variable or expression. It is often used as an alternative to multiple if-else statements when you have a variable that can take on multiple discrete values.

Syntax of the Switch Statement

switch (expression) {
    case value1:
        // Code to be executed if expression equals value1
        break; // Optional
    case value2:
        // Code to be executed if expression equals value2
        break; // Optional
    // You can have any number of case statements
    default:
        // Code to be executed if expression doesn't match any case
}

Key Points

  • The expression can be of type int, char, String, or an enumerated type (enum).
  • Each case statement checks for a specific value.
  • The break statement is used to exit the switch block. If omitted, execution will continue to the next case (this is known as "fall-through").
  • The default case is optional and will execute if none of the case values match the expression.

Example 1: Using Switch with Integer

public class SwitchExample {
    public static void main(String[] args) {
        int day = 3;
        String dayName;

        switch (day) {
            case 1:
                dayName = "Monday";
                break;
            case 2:
                dayName = "Tuesday";
                break;
            case 3:
                dayName = "Wednesday";
                break;
            case 4:
                dayName = "Thursday";
                break;
            case 5:
                dayName = "Friday";
                break;
            case 6:
                dayName = "Saturday";
                break;
            case 7:
                dayName = "Sunday";
                break;
            default:
                dayName = "Invalid day";
                break;
        }

        System.out.println("Day " + day + " is " + dayName);
    }
}

Example 2: Using Switch with String

public class SwitchStringExample {
    public static void main(String[] args) {
        String fruit = "Apple";

        switch (fruit) {
            case "Apple":
                System.out.println("You selected Apple.");
                break;
            case "Banana":
                System.out.println("You selected Banana.");
                break;
            case "Cherry":
                System.out.println("You selected Cherry.");
                break;
            default:
                System.out.println("Unknown fruit.");
                break;
        }
    }
}

Example 3: Fall-Through Behavior

public class FallThroughExample {
    public static void main(String[] args) {
        int number = 2;

        switch (number) {
            case 1:
                System.out.println("Number is 1");
                break;
            case 2:
            case 3:
                System.out.println("Number is 2 or 3");
                // No break here, so it will fall through to the next case
            case 4:
                System.out.println("Number is 4");
                break;
            default:
                System.out.println("Number is not 1, 2, 3, or 4");
                break;
        }
    }
}

Conclusion

The switch statement is a powerful tool for handling multiple conditions in a clean and organized manner. It can improve the readability of your code, especially when dealing with multiple discrete values. However, it's important to use it judiciously, as sometimes if-else statements may be more appropriate, especially for complex conditions.

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