Switch expressions in Java 12

24 Oct 2023

switch

Java 12 introduced an enhancement to the switch statement called switch expressions. This new feature allows us to use the switch statement as an expression, which means we can assign the result of the switch statement to a variable.

Syntax

The syntax for switch expressions in Java 12 is as follows:

variable = switch (expression) {
    case constant1 -> expression1;
    case constant2, constant3 -> expression2;
    // ...
    default -> expressionN;
};

The variable on the left-hand side of the assignment operator (=) is assigned the value of the expression that matches one of the case constants. The case labels are followed by the arrow (->) that separates them from the corresponding expressions.

We can have multiple case constants separated by commas, which means they will execute the same expression. Also, unlike the traditional switch statement, we don’t need to include a break statement at the end of each case.

The default keyword is used to specify the expression that is executed if none of the case constants match the given expression.

Examples

Let’s look at a few examples to understand how switch expressions work:

Example 1: Assigning a value based on a condition

String fruit = switch (day) {
    case "Monday" -> "Banana";
    case "Tuesday", "Wednesday" -> "Apple";
    case "Thursday" -> "Orange";
    case "Friday", "Saturday" -> "Mango";
    default -> "Unknown";
};

In this example, the value of fruit will be assigned based on the value of the day variable. If day is “Monday”, the value will be “Banana”, if day is “Tuesday” or “Wednesday”, the value will be “Apple”, and so on.

Example 2: Returning a value from a method

public int getMonthNumber(String month) {
    return switch (month) {
        case "January" -> 1;
        case "February" -> 2;
        case "March" -> 3;
        // ...
        default -> -1;
    };
}

In this example, the getMonthNumber method returns the corresponding number for the given month name. If the month is not recognized, it returns -1.

Benefits of Switch Expressions

Switch expressions provide several benefits over the traditional switch statement:

They improve code readability by allowing us to write concise and expressive code.
They allow us to perform complex operations within the switch statement, including calculations, method calls, and even other nested switch expressions.
They are more flexible and eliminate the need for the break statement, resulting in less error-prone code.
They can be used as a normal expression, which means they can be assigned to a variable or used inside other expressions.

Conclusion

Switch expressions in Java 12 are a powerful enhancement to the switch statement, allowing us to write more concise and flexible code. They provide improved readability and allow us to perform complex operations within the switch statement itself. It’s a valuable addition to the Java language and a feature worth exploring in your projects.

References:

#java #switch-expression