Using Switch

In Java, a switch statement is a control flow construct used for making decisions based on the value of a variable or expression.

It allows you to specify multiple possible execution paths based on the value of the expression.

The switch statement is often used as an alternative to a series of if-else if-else statements when you have a single variable to test against multiple values.

It's important to note that switch cases in Java only work with certain data types like int, char, byte, short, and enum, as well as their corresponding wrapper classes (e.g., Integer, Character, etc.)

Switch Syntax

switch (expression) {
    case value1:
        // Code to execute if expression matches value1
        break;
    case value2:
        // Code to execute if expression matches value2
        break;
    // More cases as needed
    default:
        // Code to execute if none of the cases match
}

Example:

Code

int dayOfWeek = 3;

switch (dayOfWeek) {
    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;
    default:
        System.out.println("Invalid day");
}

Explanation

In this example, the switch statement is used to print the day of the week based on the value of the dayOfWeek variable.

The break statement is used to exit the switch block after each case is executed.

If none of the cases match, the code in the default block is executed.

Aside: Java 12 Switch Cases

Starting from Java 12, switch expressions allow you to use a wider range of data types.

Here's a quick example using switch expressions introduced in Java 12:

String fruit = "apple";

String result = switch (fruit) {
    case "apple" -> "It's an apple.";
    case "banana" -> "It's a banana.";
    case "cherry" -> "It's a cherry.";
    default -> "Unknown fruit.";
};

System.out.println(result);

In this case, the switch expression assigns a value to the result variable based on the value of the fruit variable. This feature simplifies switch usage and allows you to assign values directly to variables.