How do I return an array of words given an input sentence (string)?

Question

How do I create a method that takes a string as an argument, and returns the array whose elements are the words in the string.

This is what I have came up with so far:

// split takes some string as the argument, and returns the array
// whose elements are the words in the string
public static String[] split (String s)
{
    // determine the number of words
    java.util.Scanner t = new java.util.Scanner (s);
    int countWords = 0;
    String w;
    while (t.hasNext ())
    {
        w = t.next ();
        countWords++;
    }
    // create appropriate array and store the string’s words in it
    // code here
}

As you can see, I can just input each word via Scanner. Now I just have to put all the words of the String into an array as the elements. However, I'm not sure how to proceed.

Use the ready `split` method: `str.split("\\s+");`. – Maroun Jan 02 '15 at 16:16 — Maroun, Jan 02 '15 at 16:16

cнŝdk · Answer 1 · 2015-07-10T08:48:14.663

4

You can use StringTokenizer in java to devide your string into words:

StringTokenizer st = new StringTokenizer(str, " ");

And your output st whould be an array of words.

Take a look at this Java StringTokenizer tutorial for further information.

Your code whould look like:

    StringTokenizer st = new StringTokenizer(s, " ");
    int n=st.countTokens();
    for(int i=0;i<n;i++) {
       words[i]=st.nextToken();// words is your array of words
    }

edited Jul 10 '15 at 08:48

answered Jan 02 '15 at 16:22

cнŝdk

28,676
7
47
67

2

Note the [javadoc](http://docs.oracle.com/javase/7/docs/api/java/util/StringTokenizer.html) actually recommends using `split` over this legacy class :) – Reimeus Jan 02 '15 at 16:50
Thanks @Reimeus: I will keep it in mind. And Split() seems to be faster too referring to [this](http://stackoverflow.com/questions/5965767/performance-of-stringtokenizer-class-vs-split-method-in-java). – cнŝdk Jan 02 '15 at 17:00

Christian · Answer 2 · 2015-01-02T16:28:27.227

As Maroun Maroun commented, you should use the split(regex) method from Strings, but if you want to do this by yourself:

First, declare the array:

String[] words = new String[50]; // Since you are using an array you have to declare
                                 // a fixed length.
                                 // To avoid this, you can use an ArrayList 
                                 // (dynamic array) instead.

Then, you can fill the array inside the while loop:

while (t.hasNext()) {
    w = t.next();
    words[countWords] = w;
    countWords++;
}

And finally return it:

return words;

Note:

The sentences

words[countWords] = w;
countWords++;

can be simplified in

words[countWords++] = w;

score 0 · Answer 3 · answered Jan 02 '15 at 16:35

As @Maroun Maroun said: use the split function or like @chsdk said use StringTokenizer. If you want to use scanner:

public static String[] split(String s)
{
    Scanner sc = new Scanner(s);
    ArrayList<String> l = new ArrayList<String>();

    while(sc.hasNext())
    {
        l.add(sc.next());
    }

    String[] returnValue = new String[l.size()];
    for(int i = 0; i < returnValue.length; ++i)
    {
        returnValue[i] = l.get(i);
    }

    return returnValue;
}

How do I return an array of words given an input sentence (string)?

3 Answers3