Reading Char Into an Array

Question

I have the following code that needs to take 10 chars from the user and print them out in reverse order. I can't seem to get past this one syntax error for the Scanner. How can I input one char at a time? Here is what I have so far:

import java.util.Scanner;

public class ReverseOrder
{
   //-----------------------------------------------------------------
   //  Reads a list of char from user and prints in reverse.
   //-----------------------------------------------------------------
   public static void main (String[] args)
   {
      Scanner scan = new Scanner (System.in);

      char[] letters = new char[10];

      System.out.println ("The size of the array: " + letters.length);
      for (int index = 0; index < letters.length; index++)
      {
         System.out.print ("Enter number " + (index+1) + ": ");
         letters[index] = scan.nextchar(); //doesnt like this line
      }

      System.out.println ("The numbers in reverse order:");

      for (int index = letters.length-1; index >= 0; index--)
         System.out.print (letters[index] + "  ");
   }
}

Also, see http://stackoverflow.com/questions/18746185/why-doesnt-the-scanner-class-have-a-nextchar-method and http://stackoverflow.com/questions/2597841/scanner-method-to-get-a-char and http://stackoverflow.com/questions/19417813/compiler-says-java-code-is-invalid/19417824#19417824 — Justin, Nov 14 '13 at 23:53

score 2 · Answer 1 · answered Nov 15 '13 at 00:07

2

You can also print them out in reverse order without using a loop :

System.out.println("The numbers in reverse order:");
System.out.println(new StringBuilder(new String(letters)).reverse())

answered Nov 15 '13 at 00:07

PierreF

2,250
4
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1

That is a good point. However, it is not the question. The asker is asking how to use a something like `Scanner.nextChar()` – Justin Nov 15 '13 at 00:25

knordbo · Answer 2 · 2013-11-14T23:48:20.800

1

Unfortunately, nextChar() is not a method. This can be solved using next().charAt(0) instead!

public class ReverseOrder
{
    //-----------------------------------------------------------------
    //  Reads a list of char from user and prints in reverse.
    //-----------------------------------------------------------------
    public static void main (String[] args)
    {
      Scanner scan = new Scanner (System.in);

      char[] letters = new char[10];

      System.out.println ("The size of the array: " + letters.length);
      for (int index = 0; index < letters.length; index++)
      {
         System.out.print ("Enter number " + (index+1) + ": ");
         letters[index] = scan.next().charAt(0);

      }

      System.out.println ("The numbers in reverse order:");

      for (int index = letters.length-1; index >= 0; index--)
         System.out.print (letters[index] + "  ");
    }
}

edited Nov 14 '13 at 23:48

answered Nov 14 '13 at 23:43

knordbo

562
3
7

How can I read in "chars"? – Lou44 Nov 14 '13 at 23:43
why creating a String "in" if you just can call >> char c = scan.nextLine().charAt(0); << ? – user2664856 Nov 14 '13 at 23:49
@user2664856 I just edited his code at first, updated it and simplified it now. In the end it doesn't really matter does it? It's all the readability vs code elegance discussion all over again ;) – knordbo Nov 14 '13 at 23:50
im not 100% sure, but creating a String everytime should consume a little performance. – user2664856 Nov 14 '13 at 23:52
@user2664856 You might be right. In this simple program I wouldn't really consider that factor. In that case Scanner should never be used, since it's incredibly slow. BufferedReader etc. would be preferred when you know what data to expect, like in this case. – knordbo Nov 14 '13 at 23:54
right. i just wanted to avoid adapting bad habits ;) – user2664856 Nov 14 '13 at 23:56

user987339 · Answer 3 · 2013-11-15T00:31:07.747

1

You can use in your case:

letters[index] = scan.nextLine().charAt(0);

as a replacement for scan.nextchar();

edited Nov 15 '13 at 00:31

answered Nov 14 '13 at 23:43

user987339

9,680
8
38
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score 0 · Accepted Answer · answered Nov 14 '13 at 23:47

0

char c = scan.nextLine().charAt(0);

it has to be charAt(0) not charAt(index), because he always wants the first letter.

answered Nov 14 '13 at 23:47

user2664856

600
13
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I got it running. Thank you and everyone for their help! – Lou44 Nov 15 '13 at 00:01
please choose an answer that you accept on that question. thanks – user2664856 Nov 15 '13 at 00:02

Reading Char Into an Array

4 Answers4