java switch

Java Switch Statements

Use the switch statement to select one of many code blocks to be executed.

Syntax

switch(expression) {

  case x:

    // code block

    break;

  case y:

    // code block

    break;

  default:

    // code block

}

This is how it works:

The switch expression is evaluated once.

The value of the expression is compared with the values of each case.

If there is a match, the associated block of code is executed.

The break and default keywords are optional, and will be described later in this chapter

The example below uses the weekday number to calculate the weekday name:

Example

int day = 4;

switch (day) {

  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;

}

// Outputs "Thursday" (day 4)

Try it Yourself »

The break Keyword

When Java reaches a break

keyword, it breaks out of the switch block.

This will stop the execution of more code and case testing inside

the block.

When a match is found, and the job is done, it's time for a break. There is no need for more testing.

A break can save a lot of execution time because it "ignores" the execution

of all the rest of the code in the switch block.

The default Keyword

The default keyword specifies some code to run if there is no

case match:

Example

int day = 4;

switch (day) {

  case 6:

    System.out.println("Today is Saturday");

    break;

  case 7:

    System.out.println("Today is Sunday");

    break;

  default:

    System.out.println("Looking forward to the Weekend");

}

// Outputs "Looking forward to the Weekend"

Try it Yourself »

Note that if the default statement is used

as the last statement in a switch block, it does not need a break.

Test Yourself With Exercises

Exercise:

Insert the missing parts to complete the following switch statement.

Start the Exercise