CODEWITHSUNDEEP
javaarrays
user2140783
user2140783

Reputation: 39

Duplicates in an array not to be printed more than once

The code below prints all the words from a file(puts it in 1st array) and the number one beside it(second array). If there is a duplicate of the word it finds that word(the very first one) that is in the array and adds 1 to the number array but it still prints out the duplicate in the array. I only want the first instance of the word with the correct number beside it to say how many times in has been in the array. My problem really is i don't want duplicates to be printed out. (No arraylists plz).

while ((in.hasNext())) {

    l = in.next() ;

    for(int i = 0; i< Wrd.length-1;i++){
        if (l.equals(Wrd[i])){
            num[i] = num[i] +1;
        } 

    }

    Wrd[n]=l;
    num[n] = num;

    n++;

}

Upvotes: 0

Views: 2165

Answers (3)

Sean Landsman
Sean Landsman

Reputation: 7179

It sounds like you're not able to use a Set or Map etc - if you can then the other suggestions here are much easier to implement what I'm going to suggest :-)

If you cant for some reason, then how about this:

// capture all the words first into an array
// the array below is for test purposes
String[] words = {"1", "2", "3", "5", "1", "1", "3", "4", "1", "5", "7", "0"};

Arrays.sort(words);  // sort the array - this is vital or the rest wont work
String last = words[0];
int count = 0;
for (String word : words) {
    if (word.equals(last)) {
        count++;
    } else {
        System.out.println(last + "=>" + count);

        count = 1;
        last = word;
    }
}
System.out.println(last + "=>" + count);

The output would be:

0=>1
1=>4
2=>1
3=>2
4=>1
5=>2
7=>1

Upvotes: 1

Boris the Spider
Boris the Spider

Reputation: 61148

You need to use a map - this is automatically deal with maintaining a unique list of words. If you override the put method to aggregate rather than overwrite then it will add up the count automatically.

private void readWords(final Iterator<String> in) {
    final Map<String, Integer> wordMap = new HashMap<String, Integer>() {
        @Override
        public Integer put(String key, Integer value) {
            final Integer origValue = get(key);
            if (origValue == null) {
                return super.put(key, value);
            } else {
                return super.put(key, origValue + value);
            }
        }
    };
    while (in.hasNext()) {
        wordMap.put(in.next(), 1);

    }
    //just for display - not necessary
    for (final Entry<String, Integer> entry : wordMap.entrySet()) {
        System.out.println("Word '" + entry.getKey() + "' appears " + entry.getValue() + " times.");
    }
}

Test:

List<String> strings = new LinkedList<String>();
strings.add("one");
strings.add("two");
strings.add("two");
strings.add("three");
strings.add("three");
strings.add("three");
readWords(strings.iterator());

Output:

Word 'two' appears 2 times.
Word 'one' appears 1 times.
Word 'three' appears 3 times.

You can sort the words alphabetically using a TreeMap rather than a HashMap - this may look better for display; depending on what you plan to do with the map.

Upvotes: 0

thegrinner
thegrinner

Reputation: 12243

Track if a given word is a duplicate using a boolean flag and don't add it to the array if it is:

while (in.hasNext()) {
    boolean dup = false;
    l = in.next() ;

    for(int i = 0; i< Wrd.length-1;i++){
        if (l.equals(Wrd[i])){
            num[i] = num[i] +1;
            dup = true;
            break; // No reason to check the rest of the array
        } 
    }

    if (!dup) {
        Wrd[n] = l;
        num[n] = num; // If you're looking for frequency, you probably want 1 not num

        n++; // only increment the index if we add a new word
    }
}

Upvotes: 0

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