Java Tutorial - Java Switch

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://fromwww.java2s.com
 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:/*www.java2s.com*/
 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.java2s.com
 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.

//fromwww.java2s.com
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.

//fromwww.java2s.com
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.