Java Tutorial Java Advanced Java References

Java - Switch



The Switch statement in Java language is used to execute one of many code statements. It can be considered as group of If-else statements.

Syntax

switch (expression){
  case 1:
     statement 1;
     break;
  case 2:
     statement 2;
     break;
     ...
     ...
     ...
  case N:
     statement N;
     break;
  default:
     default statement;
} 

The switch expression is evaluated and matched with the cases. When the case matches, the following block of code is executed.

Flow Diagram:

Java Switch

Example:

In the example below, the switch expression is a variable called i with value 2 which is matched against case values. When the case value matches with expression value, the following block of code is executed.

public class MyClass {
  public static void main(String[] args) {
    int i = 2;
    switch(i){
      case 1: 
         System.out.println("Red");
         break; 
      case 2: 
         System.out.println("Blue");
         break;
      case 3: 
         System.out.println("Green");
    }  
  }
}

The output of the above code will be:

Blue

default and break statements

Default case and break statement are optional here.

  • Default Case: Default Statement is executed when there is no match between switch expression and test cases.
  • Break Statement: Break statement is used to get out of the Switch statement after a match is found.

Example:

In the example below, the switch expression is a variable called i with value 10 which is matched against case values. As there is no case that matches with value 10, hence default block of code gets executed.

public class MyClass {
  public static void main(String[] args) {
    int i = 10;
    switch(i){
      case 1: 
         System.out.println("Red");
         break; 
      case 2: 
         System.out.println("Blue");
         break;
      case 3: 
         System.out.println("Green");
         break;
      default:
         System.out.println("No match found.");
    }  
  }
}

The output of the above code will be:

No match found.

Please note that, the default statement can be placed at any position in the switch statement. In such instances, add break statement with default statement.

Example:

Consider the example below, where default statement is placed on the top in a switch statement.

public class MyClass {
  public static void main(String[] args) {
    int i = 10;
    switch(i){
      default:
         System.out.println("No match found."); 
         break;
      case 1: 
         System.out.println("Red");
         break; 
      case 2: 
         System.out.println("Blue");
         break;
      case 3: 
         System.out.println("Green");
    }  
  }
}

The output of the above code will be:

No match found.

Common code blocks

There are instances where same code block is required in multiple cases.

Example:

In the example below, same code block is shared for different switch cases.

public class MyClass {
  public static void main(String[] args) {
    int i = 10;
    switch(i){
      case 1: 
         System.out.println("Red");
         break; 
      case 2:
      case 10: 
         System.out.println("Blue");
         break;
      case 3:
      case 4:
      case 5: 
         System.out.println("Green");
    }  
  }
}

The output of the above code will be:

Blue

5