Java Masterclass for Software Developers/

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The switch Statement

The switch Statement

In this lesson, we will introduce the Java switch statement that provides a clear way to define a multiway decision.

We'll cover the following...

What is a switch statement?

We can use a switch statement when a decision depends on the value of an expression. This value’s data type must be either

  • char
  • An integer type such as int
  • An enumeration, or
  • A string

Example 1

For example, if the int variable dayNumber has a value ranging from 1 to 7 to indicate one of the days Sunday through Saturday, we need not use an if-else statement to produce the day of the week as a string. Instead, we can use the following switch statement:

Java
public class Example1
{
   public static void main(String args[]) 
   {
      // Assume that dayNumber contains an integer that ranges from 1 to 7.
      int dayNumber = 5;   // Fee free to change this value.
      String dayName = null;
      switch (dayNumber) 
      {
         case 1:
            dayName = "Sunday";
            break;
         case 2:
            dayName = "Monday";
            break;
         case 3:
            dayName = "Tuesday";
            break;
         case 4:
            dayName = "Wednesday";
            break;
         case 5:
            dayName = "Thursday";
            break;
         case 6:
            dayName = "Friday";
            break;
         case 7:
            dayName = "Saturday";
            break;
         default:
            dayName = "ERROR";
            assert false: "Error in dayNumber: " + dayNumber;
            break;
      } // End switch
      System.out.println("Day " + dayNumber + " is a " + dayName); 
  } // End main
} // End Example1

In this example, dayNumber is the expression that is tested. We must be able to list the values of the expression to be able to use a switch statement. Such is the situation here since dayNumber has one of the values 1 through 7. Each value of the tested expression corresponds to a case within the switch statement. When the value of the expression matches the value in a case—called the case ...