Finding the number of words in a string

Question

I can't seem to figure out why this doesn't work, but I may have just missed some simple logic. The method doesn't seem to find the last word when there isn't a space after it, so i'm guessing something is wrong with i == itself.length() -1 , but it seems to me that it would return true; you're on the last character and it isn't a whitespace.

public void numWords()
{
    int numWords = 0;
    for (int i = 1; i <= itself.length()-1; i ++)
    {
        if (( i == (itself.length() - 1) || itself.charAt (i) <= ' ') && itself.charAt(i-1) > ' ')
            numWords ++;
    }
    System.out.println(numWords);
}

itself is the string. I am comparing the characters the way I am because that's how it is shown in the book, but please let me know if there are better ways.

http://stackoverflow.com/questions/8924599/how-to-count-the-exact-number-of-words-in-a-string-that-has-empty-spaces-between — HpTerm, Jan 28 '14 at 18:20
Can't you just split on white space? http://stackoverflow.com/questions/225337/how-do-i-split-a-string-with-any-whitespace-chars-as-delimiters — plalx, Jan 28 '14 at 18:22
Thanks for the link, I didn't see that with my brief search. — user2034276, Jan 28 '14 at 18:25

score 1 · Answer 1 · answered Jan 28 '14 at 18:20

1

Naïve approach: treat everything that has a space following it as a word. With that, simply count the number of elements as the result of a String#split operation.

public int numWords(String sentence) {
    if(null != sentence) {
        return sentence.split("\\s").length;
    } else {
        return 0;
    }
}

answered Jan 28 '14 at 18:20

Makoto

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That's super cool, thanks I'm new and havn't seen that before. – user2034276 Jan 28 '14 at 18:28

score 0 · Answer 2 · answered Jan 28 '14 at 18:24

0

Try,

int numWords = (itself==null) ? 0 : itself.split("\\s+").length;

answered Jan 28 '14 at 18:24

Rakesh KR

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score 0 · Answer 3 · answered Jan 28 '14 at 18:25

So basically what it seems you're trying to do it to count all chunks of whitespace in a string. I'll fix up your code and use my head compiler to help you out with the problems you're experiencing.

public void numWords()
{
    int numWords = 0;
    // Don't check the last character as it doesn't matter if it's ' '
    for (int i = 1; i < itself.length() - 1; i++)
    {
        // If the char is space and the next one isn't, count a new word
        if (itself.charAt(i) == ' ' && itself.charAt(i - 1) != ' ') {
            numWords++;
        }
    }
    System.out.println(numWords);
}

This is a very naive algorithm and fails in a few cases, if the string ends in multiple spaces for example 'hello world ', it would count 3 words.

Note that if I was going to implement such a method I would go with a regex approach similar to Makoto's answer in order to simplify the code.

Thank you, I appreciate the comments – user2034276 Jan 28 '14 at 18:32 — user2034276, Jan 28 '14 at 18:32

score 0 · Answer 4 · answered Jan 28 '14 at 18:26

The following code fragment does job better:

if(sentence == null) {
    return 0;
}
sentence = sentence.trim();
if ("".equals(sentence)) {
    return 0;
}
return sentence.split("\\s+").length;

The regex \\s+ works correctly in case of several spaces. trim()
removes trailng and leading spaces Additional empty line check
prevents result 1 for empty string.

Finding the number of words in a string

4 Answers4