Removing repeated characters, preserving order

Question

I'm trying to write a code that takes in a String and removes repeating characters in that String.

String utenRepetisjon(String tekst) {

    String b;

    char[] tekstArray = tekst.toCharArray();
    char[] tilTekst = new char[tekstArray.length];

    for(int i=0; i<tekstArray.length; i++) {
        for(int j=0; j<tekst.length(); j++) {
            if(tekstArray[i] != tekst.charAt(j)) {
                tilTekst[i] = tekstArray[i];
            }
        }
    }
    return b = new String(tilTekst);
}

E.g. If tekst = "aababbabbac", it should return "abc". So far my code only return the same tekst that it's given..

Take a look at this link: http://stackoverflow.com/questions/4989091/removing-duplicates-from-a-string-in-java — T0to, Nov 28 '13 at 15:38
How is your code supposed to work? tilTekst is created with the same length as tekst, which makes no sense in your problem because returned string is quite often smaller. — Pierre Arlaud, Nov 28 '13 at 15:40

score 5 · Accepted Answer · answered Nov 28 '13 at 15:40

5

Try the next:

String utenRepetisjon(String tekst) {
    String str = "";
    for(char ch : tekst.toCharArray()) {
        if (str.indexOf(ch) == -1) {
            str += ch;
        }
    }
    return str;
}

answered Nov 28 '13 at 15:40

Paul Vargas

41,222
15
102
148

2

Would be nicer with a `StringBuilder` or a character array. But it works. – Duncan Jones Nov 28 '13 at 15:41
+1 for an elegant solution. – Alexis C. Nov 28 '13 at 15:42
2

Nice, short solution. But it might suffer from the infamous String-concatenation problem when tekst is very long. StringBuilder doesn't work as it does not have a indexOf(char). – isnot2bad Nov 28 '13 at 15:42
Thank you! This one does the job :) – patski Nov 28 '13 at 15:44
Suggestion: Use StringBuilder for concatenation and write a helper-method 'contains(StringBuilder, char)'. – isnot2bad Nov 28 '13 at 15:45

score -1 · Answer 2 · answered Nov 28 '13 at 15:43

-1

Here's the code. Use a hashmap

 String tekst = "aababbabbac";
    char[] testArray = tekst.toCharArray();
    Hashtable<String, String> hash = new Hashtable<String, String>();
    for (char c : testArray) {
        if (!hash.containsKey("" + c)) {
            hash.put("" + c, "1");
        }
    }
    String dups = "";
    for (String key : hash.keySet()) {
        dups+=key;
    }
    System.out.println(dups);

answered Nov 28 '13 at 15:43

sanket

789
4
16

1

That prints bac not abc. You need to maintain the order of the letters in the original word (not the downvoter). – Alexis C. Nov 28 '13 at 15:44
Ya. I thought he wanted to just filter duplicates...And thanks for the negative !! – sanket Nov 28 '13 at 15:45
I'm not the downvoter btw. – Alexis C. Nov 28 '13 at 15:46
2

Someone who agrees with my comment ? – Alexis C. Nov 28 '13 at 15:47
1

Change to `java.util.LinkedHashSet` for maintains the order in which elements were inserted. – Paul Vargas Nov 28 '13 at 15:48
+1 for reading my mind...I was just gonna say that ! – sanket Nov 28 '13 at 15:50

Removing repeated characters, preserving order

2 Answers2