Java program to build a calculator

Program for simple mathematical operations (calculator) in java

import java.util.Scanner;

public class Calculator 
{
	public static void main(String args[])
	{
		// declare here
		float a,b,res;
		char choice, ch;
		Scanner S=new Scanner(System.in);
		
		do
		{
			// prepare menu for the user to see multiple operations.
			System.out.println("\n\nMain Menu : \n1.Addition\n2.Subtraction\n3.Division\n4.Multiplication\n5.Exit\n");
			
			// enter the choice
			System.out.print("Enter your choice : ");
			
			// read the input choice value.
			choice=S.next().charAt(0);
			
			// this loop will calculate different the operations value at different dofferent values.
			switch(choice)
			{ 
			    case '1':System.out.print("Enter two numbers : ");
			    a=S.nextFloat();
			    b=S.nextFloat();	
			    res=a+b;
			    System.out.print("Result : " +res);
			    break;
			     
			     case '2':System.out.print("Enter two numbers : ");
				 a=S.nextFloat();
				 b=S.nextFloat();	
				 res=a-b;
				 System.out.print("Result : " +res);
				 break;
				    
			     case '3':System.out.print("Enter two numbers : ");
				 a=S.nextFloat();
				 b=S.nextFloat();	
				 res=a/b;
				 System.out.print("Result : " +res);
				 break;
				    
			     case '4':System.out.print("Enter two numbers : ");
				 a=S.nextFloat();
				 b=S.nextFloat();	
				 res=a*b;
				 System.out.print("Result : " +res);
				 break;
				   
			     case '5':
				 System.exit(0);
				 break;
				 default : System.out.print("Wrong Choice.....\n");
				 break;
			}
	    }
		// loop works till the number 5 not selected.
	  while(choice!=5);
	}
}

Output

Main Menu : 
1.Addition
2.Subtraction
3.Division
4.Multiplication
5.Exit

Enter your choice : 1
Enter two numbers : 2 5
Result : 7.0

Main Menu : 
1.Addition
2.Subtraction
3.Division
4.Multiplication
5.Exit

Enter your choice : 2
Enter two numbers : 8 6
Result : 2.0

Main Menu : 
1.Addition
2.Subtraction
3.Division
4.Multiplication
5.Exit

Enter your choice : 3
Enter two numbers : 10 2
Result : 5.0

Main Menu : 
1.Addition
2.Subtraction
3.Division
4.Multiplication
5.Exit

Enter your choice : 4
Enter two numbers : 5 5
Result : 25.0

Main Menu : 
1.Addition
2.Subtraction
3.Division
4.Multiplication
5.Exit

Enter your choice : 5