Error Using CharAt(0)

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#1 odtwenty4

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Posted 24 February 2007 - 09:12 AM

I'm in the inital stage of this program. I'm not getting errors, but when I excute it the program stops at the second iteration giving me this:
StringIndexOutOfBoundsException: String index out of range: 0
at java.lang.String.charAt(Unknown Source)
at HW3.main(HW3.java:21)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
>

Thank you

  
 
 import java.util.Scanner;
 public class HW3
 { public static void main (String[] args)
 {
	 int pass = 1, weight, tot_we = 0;
	 String input;
	 char choice;
	 Scanner keyboard = new Scanner (System.in);
	 
	 while (pass <= 25 || tot_we <= 1000)
	 {
	   for (int i=1; i <= 25; i++)
	   {
		 System.out.println("Passenger " + i);
		 System.out.print("\t Do you have any luggage? ");
		 input = keyboard.nextLine();
		 choice = input.charAt(0);
		 if (choice == 'Y' || choice == 'y')
		 {
		   System.out.print("\n\t How much does it weigh? ");
		   weight = keyboard.nextInt();
		 }
		 pass = pass + i;
	   }
	 }
	 System.out.println("This flight will take off with " + pass + " passengers.");
 }
 }

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#2 PennyBoki

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Posted 24 February 2007 - 09:18 AM

That means you should catch that exception.
See HERE.

This post has been edited by PennyBoki: 24 February 2007 - 09:18 AM

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#3 horace

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Posted 24 February 2007 - 09:59 AM

after you read the integer with

		   weight = keyboard.nextInt();

it leaves the newline character in the input stream so when you call nextLine()

		 input = keyboard.nextLine();
		 choice = input.charAt(0);

it returns immediatly with an empty string and the charAt() gives an StringIndexOutOfBoundsException
you need to remove the newline, e.g. add a dummy readLine() after the nextTnt()

	 while (pass <= 25 || tot_we <= 1000)
	 {
	   for (int i=1; i <= 25; i++)
	   {
		 System.out.println("Passenger " + i);
		 System.out.print("\t Do you have any luggage? ");
		 input = keyboard.nextLine();
		 choice = input.charAt(0);
		 if (choice == 'Y' || choice == 'y')
		 {
		   System.out.print("\n\t How much does it weigh? ");
		   weight = keyboard.nextInt();
		   input = keyboard.nextLine();  // read newline
		}
		 pass = pass + i;
	   }
	 }

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#4 odtwenty4

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Posted 24 February 2007 - 12:34 PM

Thank you sooo much

horace, on 24 Feb, 2007 - 10:59 AM, said:

after you read the integer with

		   weight = keyboard.nextInt();

it leaves the newline character in the input stream so when you call nextLine()

		 input = keyboard.nextLine();
		 choice = input.charAt(0);

it returns immediatly with an empty string and the charAt() gives an StringIndexOutOfBoundsException
you need to remove the newline, e.g. add a dummy readLine() after the nextTnt()

	 while (pass <= 25 || tot_we <= 1000)
	 {
	   for (int i=1; i <= 25; i++)
	   {
		 System.out.println("Passenger " + i);
		 System.out.print("\t Do you have any luggage? ");
		 input = keyboard.nextLine();
		 choice = input.charAt(0);
		 if (choice == 'Y' || choice == 'y')
		 {
		   System.out.print("\n\t How much does it weigh? ");
		   weight = keyboard.nextInt();
		   input = keyboard.nextLine();  // read newline
		}
		 pass = pass + i;
	   }
	 }

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