Java Switch Statement – How to Use a Switch Case in Java

You use the switch statement in Java to execute a particular code block when a certain condition is met.

Here's what the syntax looks like:

switch(expression) {
  case 1:
    // code block
    break;
  case 2:
    // code block
    break;
    case 3:
    // code block
    break;
  default:
    // code block
}

Above, the expression in the switch parenthesis is compared to each case. When the expression is the same as the case, the corresponding code block in the case gets executed.

If all the cases do not match the expression, then the code block defined under the default keyword gets executed.

We use the break keyword to terminate the code whenever a certain condition is met (when the expression matches with a case).

Let's see some code examples.

How to Use a Switch Case in Java

Take a look at the following code:

class CurrentMonth {
    public static void main(String[] args) {
        
        int month = 6;
        
        switch (month) {
          case 1:
            System.out.println("January");
            break;
          case 2:
            System.out.println("February");
            break;
          case 3:
            System.out.println("March");
            break;
          case 4:
            System.out.println("April");
            break;
          case 5:
            System.out.println("May");
            break;
          case 6:
            System.out.println("June");
            break;
          case 7:
            System.out.println("July");
            break;
          case 8:
            System.out.println("August");
            break;
          case 9:
            System.out.println("September");
            break;
          case 10:
            System.out.println("October");
            break;
          case 11:
            System.out.println("November");
            break;
          case 12:
            System.out.println("December");
            break;
            
            // June
        }
    }
}

In the code above, June is printed out. Don't worry about the bulky code. Here's a breakdown to help you understand:

We created an integer called month and assigned a value of 6 to it: int month = 6;.

Next, we created a switch statement and passed in the month variable as a parameter: switch (month){...}.

The value of month, which is acting as the expression for the switch statement, will be compared with every case value in the code. We have case 1 to 12.

The value of month is 6 so it matches with case 6. This is why the code in case 6 was executed. Every other code block got ignored.

Here's another example to simplify things:

class Username {
    public static void main(String[] args) {
        
        String username = "John";
        
        switch (username) {
          case "Doe":
            System.out.println("Username is Doe");
            break;
          case "John":
            System.out.println("Username is John");
            break;
          case "Jane":
            System.out.println("Username is Jane");
            break;
            // Username is John
        }
    }
}

In the example above, we created a string called username which has a value of "John".

In the switch statement, username is passed in as the expression. We then created three cases – "Doe", "John", and "Jane".

Out of the three classes, only one matches the value of username — "John". As a result, the code block in case "John" got executed.

How to Use the Default Keyword in a Switch Statement

In the examples in the previous section, our code got executed because one case matched an expression.

In this section, you'll see how to use the default keyword. You can use it as a fallback in situations where none of the cases match the expression.

Here's an example:

class Username {
    public static void main(String[] args) {
        
        String username = "Ihechikara";
        
        switch (username) {
          case "Doe":
            System.out.println("Username is Doe");
            break;
          case "John":
            System.out.println("Username is John");
            break;
          case "Jane":
            System.out.println("Username is Jane");
            break;
          default:
            System.out.println("Username not found!");
            // Username not found!
        }
    }
}

The username variable in the example above has a value of  "Ihechikara".

The code block for the default keyword will be executed because none of the cases created match the value of username.

Summary

In this article, we saw how to use the switch statement in Java.

We also talked about the switch statement's expression, cases, and default keyword in Java along with their use cases with code examples.

Happy coding!