Java Switch Statement

We have already seen how to make decisions based on some condition in the previous chapter. In this chapter, we will look at the switch statement which can be used to replace the if...else statements in some cases to reduce the complexity and improve the readability of the code.

Normally, if we have to choose one case among many choices, nested if-else or else if is used. But if the number of choices is large, switch..case is a better option as it makes code neat and easier to understand. Let’s see how.

Consider a case in which we want to print a message based on the grade of a student. We can write a program for such a case using nested if...else or else if as shown below.

class Test {

    public static void main(String[] args) {
        char grade = 'A';
        if (grade == 'A') {
            System.out.println("Excellent !");
        } else if (grade == 'B') {
            System.out.println("Outstanding !");
        } else if (grade == 'C') {
            System.out.println("Good !");
        } else if (grade == 'D') {
            System.out.println("Can do better");
        } else if (grade == 'E') {
            System.out.println("Just passed");
        } else if (grade == 'F') {
            System.out.println("You failed");
        } else {
            System.out.println("Invalid grade");
        }
    }
}

Here, we can see that if the grade of the student is ‘A’, then we are printing "Excellent !", if the grade is ‘B’, then we are printing "Outstanding !", and so on.

We can make this program more readable by using switch..case instead of else if.

Let’s have a look at the syntax of switch...case.

Java switch Syntax

switch(expression) {
    case value1:
        statement(s)
        break;
		
    case value2:
        statement(s)
        break;
		
	/* you can give any number of cases */
	
    default:
        statement(s)
}

In switch(expression), the value of the expression is compared with the values of all the cases. If the value of the expression matches the value of a case, then the statement(s) corresponding to that case are executed.

If the expression doesn’t match the value of any case, then the statement(s) corresponding to default are executed.

For example, if the value of the expression is equal to value2, then the statement(s) corresponding to the second case are executed.

Java switch Examples

class Test {

    public static void main(String[] args) {
        char grade = 'B';

        switch (grade) {
            case 'A':
                System.out.println("Excellent !");
                break;
            case 'B':
                System.out.println("Outstanding !");
                break;
            case 'C':
                System.out.println("Good !");
                break;
            case 'D':
                System.out.println("Can do better");
                break;
            case 'E':
                System.out.println("Just passed");
                break;
            case 'F':
                System.out.println("You failed");
                break;
            default:
                System.out.println("Invalid grade");
        }
    }
}

In this example, the value of the variable grade, i.e. ‘B’, is compared with the values of all the cases.

Since the value of the first case is not ‘B’, the first case is not executed. Now, since the value of the second case is ‘B’, case 'B' is executed and 'Outstanding !' gets printed. Then the break statement will terminate the flow without checking the rest of the cases. This is how it works.

This was more readable than the first program written using if/else statements.

Note that we added the break statement after each case so that the flow terminates once a case is executed.

Now let's see what happens when we don't add break after the cases.

class Test {

    public static void main(String[] args) {
        char grade = 'B';

        switch (grade) {
            case 'A':
                System.out.println("Excellent !");
            case 'B':
                System.out.println("Outstanding !");
            case 'C':
                System.out.println("Good !");
            case 'D':
                System.out.println("Can do better");
            case 'E':
                System.out.println("Just passed");
            case 'F':
                System.out.println("You failed");
            default:
                System.out.println("Invalid grade");
        }
    }
}

In the above example, the value of grade is 'B', so the control jumps to case 'B'. Since there is no break statement after any case, all the cases after case 'B' are also executed.

Always enclose character values within ' '.

Let's see another example in which the value of the expression is an integer.

class Test {

    public static void main(String[] args) {
        int i = 2;

        switch (i) {
            case 1:
                System.out.println("Number is 1");
                break;
            case 2:
                System.out.println("Number is 2");
                break;
            default:
                System.out.println("Number is greater than 2");
        }
    }
}

You have now learned about the switch statement. Try to implement the basic functionality of a calculator like addition, subtraction, etc. using this technique. You can find the solution to this problem and more problems to practice in the practice section.