Simple Command Line Calculator Using Java

  
  import java.util.Scanner;

public class SimpleCal{
 
 public static void main(String args[]){
  
  Scanner Obj=new Scanner(System.in);
  
  char operation;
  double fnum,snum,ans;
  
  
  System.out.println("\nWelcome to Simple Cal 1.0");
  
  //Selecting mathematical operation
  System.out.println("\nEnter mathematical operation you want to perform");
  System.out.println("\n(A)Enter number 1 if you want to add two numbers");
  System.out.println("(B)Enter number 2 if you want to subtract second number from first number");
  System.out.println("(C)Enter number 3 if you want to multiply two numbers");
  System.out.println("(D)Enter number 4 if you want to divide first number from second number\n");
  
  operation=Obj.next().charAt(0);
  
  //Adding two numbers
  if(operation=='1'){
   
   System.out.println("\nEnter your first number: ");
   fnum=Obj.nextDouble();
   System.out.println("Enter your second number: ");
   snum=Obj.nextDouble();
   
   ans=fnum+snum;
   
   System.out.println("\nAnswer is "+ans);
  
   
  }
  //Subtracting numbers
  else if(operation=='2'){
   
   System.out.println("\nEnter your first number: ");
   fnum=Obj.nextDouble();
   System.out.println("Enter your second number: ");
   snum=Obj.nextDouble();
   
   ans=fnum-snum;
   
   System.out.println("\nAnswer is "+ans);
   
  }
  
  //Multiplying two numbers
  else if(operation=='3'){
   
   System.out.println("\nEnter your first number: ");
   fnum=Obj.nextDouble();
   System.out.println("Enter your second number: ");
   snum=Obj.nextDouble();
   
   ans=fnum*snum;
   
   System.out.println("\nAnswer is "+ans);
   
  }
  //Dividing first numbers from second number
  else if(operation=='4'){
   
   System.out.println("\nEnter your first number: ");
   fnum=Obj.nextDouble();
   System.out.println("Enter your second number: ");
   snum=Obj.nextDouble();
   
   ans=fnum/snum;
   
   System.out.println("\nAnswer is "+ans);
   
  }else{
   
   System.out.println("\nInvalid operation");
  }
  
  
 }
 
}