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Thread: Reversing an Array

  1. #1
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    Default Reversing an Array

        public static void main(String[] args){
            Scanner input = new Scanner(System.in);
            System.out.println("Welcome to the word reversing program");
            System.out.println("First you will enter a sentence and then the letters of each word will be in the reversed order");
            System.out.print("Please enter a Sentence: ");
            String original = input.nextLine();
            wordReverse(original);
            String reverse = wordReverse(original);
            List<String> nSentence = fixOrder(reverse);
            System.out.println("Reversing the words in the sentence: " + original + ", looks like: " + nSentence );
        }
     
        public static String wordReverse(String original){
     
            StringTokenizer string = new StringTokenizer(original);
     
            Stack<Character> charStack = new Stack<Character>();
     
            while (string.hasMoreTokens()){
     
            String stack = string.nextToken();
     
            for (int i = 0; i < stack.length(); i ++){
     
            charStack.push(stack.charAt(i));
        }
            charStack.push(' ');
        }
     
            StringBuilder result = new StringBuilder();
            while(!charStack.empty()){
            result.append(charStack.pop());
        }
     
            return result.toString();   
        }
     
        public static List<String> fixOrder(String reverse){
     
            List<String> list = Arrays.asList(reverse);
            Collections.reverse(list);
     
     
           return list;
        }
    }

    The code reads as everything is fine but the output is not reversed. If the input is "hello world" the output should be "olleh dlrow". The words are reversed to "dlrow olleh" in the word reverse method. I created a fixOrder method to reverse the order of the string so the output should be "olleh dlrow". Even with the reversal in the array i am still getting the output "dlorw olleh". Any suggestions?


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    Default Re: Reversing an Array

    cross-post: reversing-array

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    Default Re: Reversing an Array

    From two different forums? I could see re-posting over and over on one forum but I went to a completely different forum. Instead of receiving help I have you tracking me down on different forums to tell me how I am wrong.

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    Default Re: Reversing an Array

    Recommended reading: The problems with cross-posting

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    Default Re: Reversing an Array

    The problem is that you are reversing the words' character order using the same Stack. So, this is what is happening:
    hello world is entered
    You take hello and put it on a stack in reverse order
    The stack looks like this -> olleh
    You then take world and put it on the same stack in reverse order
    The stack now looks like this -> dlrow olleh
    Then you pop the stack and add each element to a stringbuilder
    The string builder adds d into stringbuilder index 0 -> d
    The stringbuilder adds l into stringbuilder index 1 -> dl
    The stringbuilder add r into stringbuilder index 2 -> dlr
    Etc, until you get -> dlrow olleh
    Even in the fixOrder() method, you are using the Collections reverse() method which just does the same thing that you did in the wordReverse() method.
    You would really need to do something like putting each word into it's own variable, reversing the character order, then add the two words back together.

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