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Scanner error

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  Scanner error kalisha malama <malamakalisha@gmail.com> - 2016-07-11 12:00 -0700
    Re: Scanner error Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-07-11 15:22 -0400
    Re: Scanner error Eric Sosman <esosman@comcast-dot-net.invalid> - 2016-07-11 15:26 -0400
      Re: Scanner error Lew <lewbloch@gmail.com> - 2016-07-11 13:12 -0700
    Re: Scanner error Eric Douglas <e.d.programmer@gmail.com> - 2016-07-11 13:58 -0700

#34855 — Scanner error

Hello All,

Am so new to programming. I need your help. am getting the following error

import java.util.Scanner;

class Apples {

	public static void main(String args[]){
		Scanner myScanner = new Scanner(System.in);
		int age;
		double price = 0.00;
		char reply; 
		
		System.out.print("How old are you ?");
			age = myScanner.nextInt();
			
		System.out.print("Do you have a Coupon?(Y/N)");
			reply = myScanner.findInLine(".").charAt(0);
			
		if (age >= 13 && age <60){
			price = 9.30;
		}
		
		if (age < 13 && age >= 60){
			price = 5.90;
		}
				if (reply == 'Y' || reply == 'y'){
					price -=2.00;
				}
				
				if (reply !='Y' && reply != 'y' && 
						reply !='N' && reply !='n'){
					System.out.println("Next Serious Customer");
				}
		
		
			System.out.print ("Please Pay $");
			System.out.print ("price");
			System.out.print (".");
			System.out.println("Thank You. Enjoy Your Diner");
		}
		
	}

error message

How old are you ?21
Do you have a Coupon?(Y/N)Exception in thread "main" java.lang.NullPointerException
	at Apples.main(Apples.java:15)

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#34857

On 7/11/2016 3:00 PM, kalisha malama wrote:
> Hello All,
>
> Am so new to programming. I need your help. am getting the following error
>
> import java.util.Scanner;
>
> class Apples {
>
> 	public static void main(String args[]){
> 		Scanner myScanner = new Scanner(System.in);
> 		int age;
> 		double price = 0.00;
> 		char reply;
> 		
> 		System.out.print("How old are you ?");
> 			age = myScanner.nextInt();
> 			
> 		System.out.print("Do you have a Coupon?(Y/N)");
> 			reply = myScanner.findInLine(".").charAt(0);
> 			
> 		if (age >= 13 && age <60){
> 			price = 9.30;
> 		}
> 		
> 		if (age < 13 && age >= 60){
> 			price = 5.90;
> 		}
> 				if (reply == 'Y' || reply == 'y'){
> 					price -=2.00;
> 				}
> 				
> 				if (reply !='Y' && reply != 'y' &&
> 						reply !='N' && reply !='n'){
> 					System.out.println("Next Serious Customer");
> 				}
> 		
> 		
> 			System.out.print ("Please Pay $");
> 			System.out.print ("price");
> 			System.out.print (".");
> 			System.out.println("Thank You. Enjoy Your Diner");
> 		}
> 		
> 	}
>
> error message
>
> How old are you ?21
> Do you have a Coupon?(Y/N)Exception in thread "main" java.lang.NullPointerException
> 	at Apples.main(Apples.java:15)

     The nextInt() call consumed the "21" and returned the value 21, but
it stopped consuming input right there, without swallowing the rest of
the line (that is, without swallowing the end-of-line "sentinel," the
marker produced by ENTER or RETURN or whatever).

     Then the findInLine() call looked for a single character *in the
same line*, and didn't find one.  Failing to find one, it returned null.
As the Javadoc says,

	"If no such pattern is detected in the input up to the next
	line separator, then null is returned and the scanner's
	position is unchanged."

     Finally, the program attempts `null.charAt(0)' -- with unfortunate
but predictable results ...

     Consider using next() instead of findInLine().  (Also, consider that
"stream-oriented" Scanner may not be the best tool for "line-oriented"
input -- but maybe that's a topic for another day.)

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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#34859

On 7/11/2016 3:23 PM, Stefan Ram wrote:
> kalisha malama <malamakalisha@gmail.com> writes:
>> How old are you ?21
>> Do you have a Coupon?(Y/N)Exception in thread "main" java.lang.NullPointerException
>> 	at Apples.main(Apples.java:15)
>
>   The method declaration
>
> void f( final java.lang.CharSequence s ){ s.charAt( 0 ); }
>
>   assumes that »s« is not null, otherwise there will be an exception,
>   which is a kind of runtime error.
>
>   The code could be replaced by, for example,
>
> void f( final java.lang.CharSequence s ){ if( s != null )s.charAt( 0 ); }
>
>   .

     I, too, sometimes type faster than I think.  Will you post a
correction?

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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#34860

> if (age < 13 && age >= 60){ 

This will never evaluate to 'true'.

-- 
Lew

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#34862

On Monday, July 11, 2016 at 3:00:36 PM UTC-4, kalisha malama wrote:
> Hello All,
> 
> Am so new to programming. I need your help. am getting the following error
> 
> import java.util.Scanner;
> 
> class Apples {
> 
> 	public static void main(String args[]){
> 		Scanner myScanner = new Scanner(System.in);
> 		int age;
> 		double price = 0.00;
> 		char reply; 
> 		
> 		System.out.print("How old are you ?");
> 			age = myScanner.nextInt();
> 			
> 		System.out.print("Do you have a Coupon?(Y/N)");
> 			reply = myScanner.findInLine(".").charAt(0);
> 			
> 		if (age >= 13 && age <60){
> 			price = 9.30;
> 		}
> 		
> 		if (age < 13 && age >= 60){
> 			price = 5.90;
> 		}
> 				if (reply == 'Y' || reply == 'y'){
> 					price -=2.00;
> 				}
> 				
> 				if (reply !='Y' && reply != 'y' && 
> 						reply !='N' && reply !='n'){
> 					System.out.println("Next Serious Customer");
> 				}
> 		
> 		
> 			System.out.print ("Please Pay $");
> 			System.out.print ("price");
> 			System.out.print (".");
> 			System.out.println("Thank You. Enjoy Your Diner");
> 		}
> 		
> 	}
> 
> error message
> 
> How old are you ?21
> Do you have a Coupon?(Y/N)Exception in thread "main" java.lang.NullPointerException
> 	at Apples.main(Apples.java:15)

1. Not sure what you're trying to do with the findInLine.  Change that line to reply = myScanner.next().charAt(0); will work
2. Logic errors, as Lew points out.
3. Cannot use double for monetary.  I replaced that line and added the price variable to the print statement and got output:
Please Pay $7.300000000000001price.Thank You. Enjoy Your Diner
4. I pasted this in Eclipse and got a warning, don't forget to call myScanner.close()

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