Java Tutorial - Java Switch

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The switch statement is a multiway branch statement. It provides a better alternative than a large series of if-else-if statements.

Java switch Statement

Here is the general form of a switch statement:

switch (expression) { 
case value1: 
    statement sequence 
    break; 
case value2: 
    statement sequence 
    break; 
. 
. 
. 
case valueN: 
    statement sequence 
    break; 
default: 
    default statement sequence 
}

The value1 to valueN are the possible case values for expression. Duplicate case values are not allowed.

A break statement jumps out of switch statement to the first line that follows the entire switch statement.

Here is a simple example that uses a switch statement:

 
public class Main {
  public static void main(String args[]) {
    for (int i = 0; i < 6; i++)
      switch (i) {
        case 0://from w  ww .  j a v  a2 s.co  m
          System.out.println("i is zero.");
          break;

        case 1:
          System.out.println("i is one.");
          break;

        case 2:
          System.out.println("i is two.");
          break;

        case 3:
          System.out.println("i is three.");
          break;

        default:
          System.out.println("i is greater than 3.");
      }
  }
}

The output produced by this program is shown here:

Example

The break statement is optional. If you omit the break, execution will continue on into the next case. For example, consider the following program:

 
public class Main {
  public static void main(String args[]) {
    for (int i = 0; i < 12; i++)
      switch (i) {
        case 0:/*w  ww.j  ava2  s. c o m*/
        case 1:
        case 2:
        case 3:
        case 4:
          System.out.println("i is less than 5");
          break;
        case 5:
        case 6:
        case 7:
        case 8:
        case 9:
          System.out.println("i is less than 10");
          break;
        default:
          System.out.println("i is 10 or more");
      }
  }
}

This program generates the following output:

Example 2

Java supports the nested switch statements. For example, the following fragment is a valid nested switch statement.

public class Main {
  public static void main(String args[]) {
    for (int i = 0; i < 6; i++)
      switch(i) { 
        case 0: //  www  .  ja v a  2 s  . c  o  m
          switch(i+1) { // nested switch 
            case 0: 
              System.out.println("target is zero"); 
              break; 
            case 1: 
              System.out.println("target is one"); 
              break; 
          } 
          break; 
        case 2: // ...
     }
  }
}

The output:

Example 3

The following code shows how to switch with char value.

//from w  ww  .  j av a2  s . co m
import java.util.Scanner;

public class Main {
  static Scanner sc = new Scanner(System.in);

  public static void main(String[] args) {
    char p = 'a';

    String details = "";

    switch (p) {
    case 'E':
    case 'e':
      details += "\tE...\n";
    case 'D':
    case 'd':
      details += "\tD...\n";
    case 'C':
    case 'c':
      details += "\tC...\n";
    case 'B':
    case 'b':
      details += "\tB...\n";
    case 'A':
    case 'a':
      details += "\tA.\n";
      break;
    default:
      details = "That's";
      break;
    }
    System.out.println(details);
  }
}

The code above generates the following result.

Example 4

The following code shows how to use string literals in switch statements.

//from w ww . j  a  v  a 2s. c  om
public class Main {
  public static void main(String[] args) {
    String[] data = new String[]{"a","b","java2s.com"};
    for (String argument : data) {
      switch (argument) {
      case "a":
      case "b":
        System.out.println("a or b");
        break;
      case "java2s.com":
        System.out.println("java2s.com");
        break;
      case "-help":
        System.out.println("displayHelp");
        break;
      default:
        System.out.println("Illegal command line argument");
      }

    }
  }
}

The code above generates the following result.

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