Don't understand the purpose of charAt() and "" ..

import java.util.Scanner;
				public class CarWashApp
				{ 
				 static Scanner sc = new Scanner(System.in);
				 public static void main(String[] args)
				 {
				  System.out.println
				   ("The car wash application!\n\n");
				  System.out.print("Enter the package code: ");
				  String s = sc.next();
				  char p = s.charAt(0);
				  String details = "";
				  switch (p)
				  {
				   case 'E':
				   case 'e':
				    details += "\tNew Car Scent, plus...\n";
				   case 'D':
				   case 'd':
				    details += "\tTire Treatment, plus...\n";
				   case 'C':
				   case 'c':
				   details += 
				    "\tLeather/Vinyl Treatment, plus...\n";
				   case 'B':
				   case 'b':
				    details += "\tWax, plus...\n";
				   case 'A':
				   case 'a':
				    details += "\tWash, vacuum, and hand dry.\n";
				    break;
				   default:
				    details = "That's not one of the codes.";
				    break;
				  }
				  System.out.println("\nThat package includes:\n");
				  System.out.println(details);
				 }
				}

For the above code, we have to use charAt(0) to get the character that is entered from sc.next() right ? Is it because the Scanner class do not have a method to grab char ?

For String details = ""; , what is the purpose of "" ? I removed them and there is a slew of errors..

Thanks in advance.

WeiJie Lim wrote:
For the above code, we have to use charAt(0) to get the character that is entered from sc.next() right ? Is it because the Scanner class do not have a method to grab char ?

You can answer that for yourself. Look at the docs for Scanner. Do you see a method there that returns the first character of the input stream?

For String details = ""; , what is the purpose of "" ? I removed them and there is a slew of errors..

Local variables do not have a value until you explicitly set one. So if you just do String details;, the details variable does not have any value.

Later, when we do details += ..., that says, "take the current value of 'details', and append something to the String object stored there." However, since details doesn't have a value (because we didn't give it one), that statement cannot succeed. We can't operate on the "current value" when there is no "current value."

The = "" part says that we are assigning to the "details" variable a reference value that points to an empty String object. That is, a String object that contains no characters. In the end, we're basically saying, "Here's an empty box. Now add this stuff to whatever is in the box."

WeiJie Lim wrote:For the above code, we have to use charAt(0) to get the character that is entered from sc.next() right ? Is it because the Scanner class do not have a method to grab char ?

Yes, but you could have answered that yourself by simply looking at the API documentation.

For String details = ""; , what is the purpose of "" ? I removed them and there is a slew of errors.

.
Doesn't surprise me. Look at the rest of the code. What is it doing?

That should help you understand why the String details = ""; is there.

Winston

[Edit] Too slow.

Oh okay, thanks alot.

I should be looking to the docs more often..

For the "" part, I didn't think of the fact that it is related to a local variable =/

Sorry.