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Switch Statement

Submitted by GeePee on Saturday, June 13, 2015 - 22:32.
Introduction: Welcome to a tutorial page on how to use a Switch statement within Java. What is a Switch statement? A Switch statement is used to check multiple cases or conditions for a particular instance. In Java 7, switch statements can be used for Strings and Integers whereas older versions of Java can only use Integers in a switch statement. When is a Switch statement used? A switch statement is very similar to a If and Else If statement except using a switch statement is much cleaner, less complex and you do not have to state the variable to check each time you want to check it - this does in-turn mean that you can only use one variable per switch statement. Examples: Setting up the methods to be created as examples:
  1. System.out.println(getMonthNumber("february"));
  2. System.out.println(getMonthString(2));
Here is an integer example from the official Java Documents to convert the month integer to a string...
  1. public static String getMonthString(int month) {
  2.         String futureMonths = "";
  3.         switch (month) {
  4.                 case 1:  futureMonths = "January";
  5.         break;
  6.             case 2:  futureMonths = "February";
  7.         break;
  8.             case 3:  futureMonths = "March";
  9.         break;
  10.             case 4:  futureMonths = "April";
  11.         break;
  12.             case 5:  futureMonths = "May";
  13.         break;
  14.             case 6:  futureMonths = "June";
  15.         break;
  16.             case 7:  futureMonths = "July";
  17.         break;
  18.             case 8:  futureMonths = "August";
  19.         break;
  20.             case 9:  futureMonths = "September";
  21.         break;
  22.             case 10: futureMonths = "October";
  23.         break;
  24.             case 11: futureMonths = "November";
  25.         break;
  26.             case 12: futureMonths = "December";
  27.             break;
  28.             default: break;
  29.         }
  30.         return futureMonths;
  31. }
and here is a Java 7 example of turning a string in to an integer...
  1. public static int getMonthNumber(String month) {
  2.     int monthNumber = 0;
  3.     if (month == null) {
  4.         return monthNumber;
  5.     }
  6.     switch (month.toLowerCase()) {
  7.         case "january":
  8.             monthNumber = 1;
  9.             break;
  10.         case "february":
  11.             monthNumber = 2;
  12.             break;
  13.         case "march":
  14.             monthNumber = 3;
  15.             break;
  16.         case "april":
  17.             monthNumber = 4;
  18.             break;
  19.         case "may":
  20.             monthNumber = 5;
  21.             break;
  22.         case "june":
  23.             monthNumber = 6;
  24.             break;
  25.         case "july":
  26.             monthNumber = 7;
  27.             break;
  28.         case "august":
  29.             monthNumber = 8;
  30.             break;
  31.         case "september":
  32.             monthNumber = 9;
  33.             break;
  34.         case "october":
  35.             monthNumber = 10;
  36.             break;
  37.         case "november":
  38.             monthNumber = 11;
  39.             break;
  40.         case "december":
  41.             monthNumber = 12;
  42.             break;
  43.         default:
  44.             monthNumber = 0;
  45.             break;
  46.     }
  47.     return monthNumber;
  48. }
Which gives the combined output: 2 February Finished!

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