How do I make Scan.findInLine(word).charAt(number); Scan a known string and not an input?

[Joseph Alrawi]

Hello!

I'm having an issue with my program that needs 2 lines of input when I only want one. First I call Scan.nextLine(); to fetch a word. Then I want Scan.findInLine(word).charAt(number); to scan the string word for a letter instead of having to put another line in the console. How do I make Scan.findInLine(word).charAt(number); scan a single String instead of scanning input typed by the user? Just FYI, I have tried to read and read to find solutions, I'm currently reading Learning How To Program Java For Dummies. But I've also read online posts on similar issues, but I just don't get it, hopefully you can help!

Thanks!

[Henry Wong]

Joseph Alrawi wrote:
I'm having an issue with my program that needs 2 lines of input when I only want one. First I call Scan.nextLine(); to fetch a word. Then I want Scan.findInLine(word).charAt(number); to scan the string word for a letter instead of having to put another line in the console. How do I make Scan.findInLine(word).charAt(number); scan a single String instead of scanning input typed by the user? Just FYI, I have tried to read and read to find solutions, I'm currently reading Learning How To Program Java For Dummies. But I've also read online posts on similar issues, but I just don't get it, hopefully you can help!

The scanner class allows you to read from different types of inputs ... String, or various forms of streams, etc. However, a single Scanner instance is only configured for one source. So, if you are using a scanner instance to get a string, and then, you want to scan that string for a word, then you need to create another scanner instance using that string as the input source.

Henry

[Joseph Alrawi]

Henry Wong wrote:

Joseph Alrawi wrote:
I'm having an issue with my program that needs 2 lines of input when I only want one. First I call Scan.nextLine(); to fetch a word. Then I want Scan.findInLine(word).charAt(number); to scan the string word for a letter instead of having to put another line in the console. How do I make Scan.findInLine(word).charAt(number); scan a single String instead of scanning input typed by the user? Just FYI, I have tried to read and read to find solutions, I'm currently reading Learning How To Program Java For Dummies. But I've also read online posts on similar issues, but I just don't get it, hopefully you can help!

The scanner class allows you to read from different types of inputs ... String, or various forms of streams, etc. However, a single Scanner instance is only configured for one source. So, if you are using a scanner instance to get a string, and then, you want to scan that string for a word, then you need to create another scanner instance using that string as the input source.

Henry

Hello Henry.

I have before tired out making another scanner like:

Scanner Scan2 = new Scanner(word);¨

Using it in Scan2.findInLine(word).charAt(number);

The problem is that I get an error when running the program afterwards saying:

Exception in thread "main" java.lang.NullPointerException
at java.io.StringReader.<init>(Unknown Source)
at java.util.Scanner.<init>(Unknown Source)
at Default.Horizon.main(Horizon.java:14)


Here's my code if you need further info:

package Default;

import java.util.Scanner;
import java.util.Random;

public class Horizon {
	public static void main(String args[]) {
		String word = null;
		int length = 0;
		int number = 0;
		String answer;
		
		Scanner Scan = new Scanner(System.in);
		Scanner Scan2 = new Scanner(word);
		Random Rand = new Random();
		
		
		System.out.println
		("Hello, please type any word.");
		
		word = Scan.nextLine();
		
		length = word.length();
		
		number = Rand.nextInt(length);
		
		char letter = Scan2.findInLine(word).charAt(number);
		
		System.out.println(letter);
		
		String letter2 = Character.toString(letter);
	
		number = (number += 1);

		System.out.println
		("You have answered:");
		
		System.out.println(word);
		
		System.out.println();
		
		System.out.println
		("What letter is at the number " + number + " of the word you typed?");
		
		Scan.nextLine();
		answer = Scan.nextLine();
		
		if (answer.equals(letter2)) {
			System.out.println("You are correct.");
			
		
			} else {
				System.out.println("Wrong answer.");
			
		}
		
		
		
	}

	}

[Winston Gutkowski]

Joseph Alrawi wrote:The problem is that I get an error when running the program afterwards saying:
Exception in thread "main" java.lang.NullPointerException
at java.io.StringReader.<init>(Unknown Source)
at java.util.Scanner.<init>(Unknown Source)
at Default.Horizon.main(Horizon.java:14)

So: what is the value of 'word' at line 14?

I hope you know by now that Java passes everything (including references) by value; and if not, you should read the link (and possibly also it's "part 1" page).

HIH

Winston

[Joseph Alrawi]

Winston Gutkowski wrote:

Joseph Alrawi wrote:The problem is that I get an error when running the program afterwards saying:
Exception in thread "main" java.lang.NullPointerException
at java.io.StringReader.<init>(Unknown Source)
at java.util.Scanner.<init>(Unknown Source)
at Default.Horizon.main(Horizon.java:14)

So: what is the value of 'word' at line 14?

I hope you know by now that Java passes everything (including references) by value; and if not, you should read the link (and possibly also it's "part 1" page).

HIH

Winston

Hey, I've known that yes, I just didn't think of it at all, how embarrassing. Thanks for your help, the problem is finally fixed!

[Winston Gutkowski]

Joseph Alrawi wrote:Hey, I've known that yes, I just didn't think of it at all, how embarrassing.

Don't worry. We've all been there.

Thanks for your help, the problem is finally fixed!

Great! Glad we could help.

Winston