Find repeated substring in given string

Find repeated substring in a given string

• We can find the count of a substring in a given string by using the indexOf() method, StringUtils, patterns, and split method.

Program to find substring in a given string:

import java.util.regex.*;
import org.apache.commons.lang3.StringUtils;
public class countWord {
    public static void main(String[] args) {
    String str = "whatat at dat";
    String find = "at";

    int index = 0;
    int count5 = 0;
    while (true) {
    index = str.indexOf(find, index);
        if (index != -1) {
            count5++;
            index += find.length();
        } else {
            break;
        }
    }
    System.out.println("Find string in given string using indexOf()=" + count5);
    
    Matcher m = Pattern.compile(find).matcher(str);
    
    int count1 = 0;
    while (m.find()) {
        count1++;
    }
    System.out.println("Find string in given string using pattern=" + count1);
    
    int count2 = StringUtils.countMatches(str, find);
    System.out.println("Find string in given string using StringUtils=" + count2);
    
    Pattern pattern = Pattern.compile("[^at]*at");
    Matcher matcher = pattern.matcher(str);
    int count = 0;
    while (matcher.find()) {
        count++;
    }
    System.out.println("Find string in given string using patterns using regular expression=" + count);
    
    int count4 = str.split(find, -1).length - 1;
    //int count4=str.split(find).length - 1;
    System.out.println("Find string in given string using split method=" + count4);
    }
}

Output:

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