Java switch Statement

In Java, we have used the if..else..if ladder to execute a block of code among multiple blocks. However, the syntax of if...else...if ladders are too long.

Hence, we can use the switch statement as a substitute for long if...else...if ladders. The use of switch statements makes our code more readable.

The syntax of the switch statement is:

switch (variable/expression) {
case value1:
   // statements of case1
   break;

case value2:
   // statements of case2
   break;

   .. .. ...
   .. .. ...

default:
   // default statements
}

The switch statement evaluates the expression (mostly variable) and compares it with values (can be expressions) of each case label.

Now, if the value matches a certain case label, then all the statements of the matching case label are executed.

For example, if the variable/expression is equal to value2. In this case, all statements of that matching case (statements of case2) are executed.

Notice, the use of break statements in each case. The break statement is used to terminate the execution of the switch statement.

It is important because if break is not used all the statements after the matching case are executed in sequence until the end of the switch statement.

Flowchart of switch Statement

Example 1: Java switch statement

class Main {
    public static void main(String[] args) {

        int week = 4;
        String day;

        // switch statement to check day
        switch (week) {
            case 1:
                day = "Sunday";
                break;
            case 2:
                day = "Monday";
                break;
            case 3:
                day = "Tuesday";
                break;

            // match the value of week
            case 4:
                day = "Wednesday";
                break;
            case 5:
                day = "Thursday";
                break;
            case 6:
                day = "Friday";
                break;
            case 7:
                day = "Saturday";
                break;
            default:
                day = "Invalid day";
                break;
        }
        System.out.println("The day is " + day);
    }
}

Output:

The day is Wednesday

In the above example, we have used the switch statement to find out the day of a week. Here, we have a variable week that holds an integer value. The value is compared to each case inside the switch block.

Here the value of week is 4. Hence it matches the case 4. So the statement inside case 4 is executed.

Example 2: Making Calculator using the switch statement

The program below takes three inputs from the user: one operator and 2 numbers. Based on the operator provided by the user, it performs the calculation on the numbers. Then the result is displayed on the screen.

Before you go through the program, make sure you know about Java Scanner to take input from the user.

import java.util.Scanner;

class Main {
    public static void main(String[] args) {

        char operator;
        Double number1, number2, result;

        // create an object of Scanner class
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter operator (either +, -, * or /): ");

        // ask user to enter operator
        operator = scanner.next().charAt(0);
        System.out.print("Enter number1 and number2 respectively: ");

        // ask user to enter numbers
        number1 = scanner.nextDouble();
        number2 = scanner.nextDouble();

        switch (operator) {

            // performs addition between numbers
            case '+':
                result = number1 + number2;
                System.out.print(number1 + "+" + number2 + " = " + result);
                break;

            // performs subtraction between numbers
            case '-':
                result = number1 - number2;
                System.out.print(number1 + "-" + number2 + " = " + result);
                break;

            // performs multiplication between numbers
            case '*':
                result = number1 * number2;
                System.out.print(number1 + "*" + number2 + " = " + result);
                break;

            // performs division between numbers
            case '/':
                result = number1 / number2;
                System.out.print(number1 + "/" + number2 + " = " + result);
                break;

            default:
                System.out.println("Invalid operator!");
                break;
        }
    }
}

Output:

Enter operator (either +, -, * or /): *
Enter number1 and number2 respectively: 1.4
-5.3
1.4*-5.3 = -7.419999999999999

In the above example, we have used the switch statement to create a calculator. It performs the calculation based on the operator provided by the user.