Search string to find substring multiple times in Java

Question

I have a string, so how could I check how many times a specific substring is found in the string?

For example,

String1 = "The fox and the hound"

, and I want to know how many times the word "the" appeared.

The idea I had was since "the" has length three, I could check every set of three characters in the string, but I am hoping there is a more efficient way.

refer to indexOf(String) and indexOf(String, int) in API doc — Jigar Joshi
– Jigar Joshi, Commented Jan 21, 2015 at 23:58

Malik Brahimi · Accepted Answer · 2018-05-17 23:07:46Z

3

You can use StringUtils to count like so:

String string = "The fox and the hound".toLowerCase(); // to lower

int count = StringUtils.countMatches(string, "the"); // count is 2

edited May 17, 2018 at 23:07

answered Jan 22, 2015 at 0:05

Malik Brahimi

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MaxZoom · Accepted Answer · 2015-01-22 00:18:14Z

1

Here is a solution with regular expression:

import java.util.regex.*;

public class RegexToCountWords {
  public static final String SAMPLE_STRING = "The fox and the hound";
  public static final String SEARCH_STRING = "the";

  public static void main(String[] args) {
    // pattern to compare \\b matches word boundaries
    Pattern pattern = Pattern.compile("\\b" + SEARCH_STRING + "\\b");
    Matcher matcher = pattern.matcher(SAMPLE_STRING.toLowerCase());
    //matcher.find() checks for all occurrances
    int count = 0;
    while (matcher.find()) {
      count++;
    }
    System.out.println("Sample String : " + SAMPLE_STRING);
    System.out.println("Number of matching strings : " + count);
  }

edited Jan 22, 2015 at 0:18

answered Jan 22, 2015 at 0:02

MaxZoom

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