This example is used to show the difference between 'regex search' and 'use of indexOf'

FindingFullWord.java

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class FindingFullWord {
    public static void main(String[] args) {

        String sentence="dia India dia dialog fadia dia";
        String word="dia";
        System.out.println("count by first method =="+simpleCount(word,sentence));//count by first method ==6
        System.out.println("count by second method =="+regexCount(word,sentence));//count by second method ==3
    }

    public static int simpleCount(String subString, String string) {
        int lastIndex = 0;
        int cnt = 0;

        while (lastIndex != -1) {
            lastIndex = string.indexOf(subString, lastIndex);

            if (lastIndex != -1) {
                cnt = cnt + 1;
                lastIndex += subString.length();
            }
        }
        return cnt;
    }

    static int regexCount(String subString, String string) {
        int cnt = 0;
        String regex="\\b"+subString+"\\b";
        Pattern p = Pattern.compile(regex);
        Matcher m = p.matcher(string);
        while (m.find())
            cnt++;
        return cnt;
    }

}