Switch Case in Java programming

• The control statement that allows us to make a decision from the number of choices is called a switch, or more correctly a switch-case-default.

• The Switch executes the case where a match is found and then all subsequent cases till end, so stop that fall through we use break; statement in each case.

• A switch works with the byte, short, char, and int primitive data types.

• It also works with enumerated types , the String class, and a few special classes that wrap certain primitive types: Character, Byte, Short, and Integer.

Syntax :

switch(expression){
   case value1  :
      statement(s);
      break; //optional
   case value2  :
      statement(s);
      break; //optional
    .....
/* you can have any number of case statements. */
   default : //Optional
      statement(s);
  /* code to be executed if all cases are not matched */
}               
                                    

Block Diagram :

Example:

import java.util.Scanner;

class Test {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x;
        System.out.println("MENU\n----------");
        System.out.println("1. for Hello");
        System.out.println("2. for Bye");
        System.out.println("-----------");
        System.out.print("Enter Your Choice: ");
        x = sc.nextInt();
        switch (x) {
            case 1:
                System.out.println("HELLO USER!!");
                break;
            case 2:
                System.out.println("BYE USER!!");
                break;
            default:
                System.out.println("INVALID!!");
        }
    }
}

MENU
-----------
1. for Hello
2. for Bye
-----------
Enter Your Choice: 1
HELLO USER!!
                                

Using Strings in switch :

From Java SE 7 , you can use a String object in the switch statement's expression. The following code example, StringSwitchDemo, displays the number of the month based on the value of the String named month:

public class StringSwitchDemo {

    public static void main(String[] args) {
        String month = "august";
        switch (month) {
            case "january":
                System.out.print("1st Month");
                break;
            case "february":
                System.out.print("2nd Month");
                break;
            case "march":
                System.out.print("3rd Month");
                break;
            case "april":
                System.out.print("4th Month");
                break;
            case "may":
                System.out.print("5th Month");
                break;
            case "june":
                System.out.print("6th Month");
                break;
            case "july":
                System.out.print("7th Month");
                break;
            case "august":
                System.out.print("8th Month");
                break;
            case "september":
                System.out.print("9th Month");
                break;
            case "october":
                System.out.print("10th Month");
                break;
            case "november":
                System.out.print("11th Month");
                break;
            case "december":
                System.out.print("12th Month");
                break;
            default:
                System.out.print("wrong Month");
                break;
        }//switch closed
    }//main closed
}//class closed

 8th Month   
            

Java Nested Switch Statement

A nested switch statement is a switch statement that appears inside another switch statement's case block. It allows for more complex decision-making scenarios by evaluating multiple levels of conditions.

Example :

public class NestedSwitchExample {
    public static void main(String[] args) {
        int category = 2;
        int item = 1;

        switch (category) {
            case 1:
                switch (item) {
                    case 1:
                        System.out.println("Category: 1, Item: 1");
                        break;
                    case 2:
                        System.out.println("Category: 1, Item: 2");
                        break;
                    default:
                        System.out.println("Invalid Item for Category 1");
                        break;
                }
                break;
            case 2:
                switch (item) {
                    case 1:
                        System.out.println("Category: 2, Item: 1");
                        break;
                    case 2:
                        System.out.println("Category: 2, Item: 2");
                        break;
                    default:
                        System.out.println("Invalid Item for Category 2");
                        break;
                }
                break;
            default:
                System.out.println("Invalid Category");
                break;
        }
    }
}