Question

public class Anagram {
    public static void main(String[] args) {

        String a = "Despera tion-".toLowerCase();
        String b = "A Rope Ends It".toLowerCase();

        String aSorted = sortStringAlphabetically(a);
        String bSorted = sortStringAlphabetically(b);

        if(aSorted.equals(bSorted)){
            System.out.println("Anagram Found!");
        }else{
            System.out.println("No anagram was found");
        }

    }

    public static String sortStringAlphabetically(String s) {

        char[] ca = s.toCharArray();
        int cnt = 0;
        ArrayList al = new ArrayList();

        for (int i = 0; i < ca.length; i++) {
            if (Character.isLetter(ca[cnt])) 
                al.add(ca[cnt]);

            cnt++;
        }

        Collections.sort(al);
        return al.toString();
    }
}

As a learner, I hacked up this boolean Anagram checker. My chosen solution was to create a sortStringAlphabetically method seems to do just too much type-juggling String -> chars[] -> ArrayList ->String – given that I do just want to compare 2 strings to test whether one phrase is an anagram of another – could I have done it with less type-juggling?

ps The tutors solution was a mile away from my attempt, and probably much better for a lot of reasons – but I am really trying to get a handle on all the different Collection types.

http://www.home.hs-karlsruhe.de/~pach0003/informatik_1/aufgaben/en/doc/src-html/de/hska/java/exercises/arrays/Anagram.html#line.18

EDIT

FTW here is the original challenge, I realise I wandered away from the solution.

http://www.home.hs-karlsruhe.de/~pach0003/informatik_1/aufgaben/en/arrays.html

My initial kneejerk reaction was to simply work though array a, knocking out those chars which matched with array b – but that seemingly required me to rebuild the array at every iteration – Many thanks for all your efforts to educate me.

Answer 1

There are different ways to improve this, if you go with this algorithm.
First, you don’t necessarily need to create a character array. You can use String.charAt() to access a specific character of your string.

Second, you don’t need a list. If you used a SortedMultiSet or a SortedBag, you could just add things in sorted order. If you write a function that creates the SortedMultiSet from your string, you could just compare the sets without rebuilding the string.

Note: I don’t know what libraries you’re allowed to use (Google and Apache have these types), but you can always ‘brew your own’.

Also, make sure to use generics for your types. Just defining ArrayLists is pretty risky, IMHO.