Java switch Statement

In this chapter you will learn:

What is the Java Switch Statement Syntax
How to use the optional break statement
How to write nested switch Statements

Java Switch Statement Syntax

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

switch (expression) { 
case value1: /*from   j  a v  a 2  s. c om*/
    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   j av  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:

Optional break statement

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:/*  j  a  v a 2  s  .  c om*/
        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:

Nested switch Statements

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: //from  java  2 s .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:

Next chapter...

What you will learn in the next chapter:

Java switch Statement