Finding second occurrence of a substring in a string in Java

Question

We are given a string, say, "itiswhatitis" and a substring, say, "is". I need to find the index of 'i' when the string "is" occurs a second time in the original string.

String.indexOf("is") will return 2 in this case. I want the output to be 10 in this case.

score 213 · Accepted Answer · edited Oct 05 '18 at 19:01

213

Use overloaded version of indexOf(), which takes the starting index (fromIndex) as 2nd parameter:

str.indexOf("is", str.indexOf("is") + 1);

edited Oct 05 '18 at 19:01

Itso Ivanov

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answered Sep 26 '13 at 18:30

Rohit Jain

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14

This is ingenious. – sofs1 Mar 09 '19 at 22:41

score 57 · Answer 2 · answered Feb 02 '16 at 13:37

57

I am using: Apache Commons Lang: StringUtils.ordinalIndexOf()

StringUtils.ordinalIndexOf("Java Language", "a", 2)

answered Feb 02 '16 at 13:37

To Kra

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3
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1

Nice and clear, thanks! – Osmar Jan 18 '22 at 03:39

score 37 · Answer 3 · answered Sep 26 '13 at 18:30

37

int first = string.indexOf("is");
int second = string.indexOf("is", first + 1);

This overload starts looking for the substring from the given index.

answered Sep 26 '13 at 18:30

Jeroen Vannevel

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what if the occurence is more than twice? – Pravat Panda Sep 26 '13 at 18:33
2

Then nothing special happens, it will still take the second occurence. – Jeroen Vannevel Sep 26 '13 at 18:34
2

what about the index of third occurence! – Pravat Panda Sep 26 '13 at 18:34
7

What about it? The question was to find the second occurence. – Jeroen Vannevel Sep 26 '13 at 18:35
1

i mean what if 10 occcurences are there in the string – Pravat Panda Sep 26 '13 at 18:35
3

@PravatPanda: I guess you want to know how to get the third occurence? Then you could just continue the code in Jeroen's answer and add a third `string.indexOf("is", second + 1);` although it would probably be better to make a method that returns the Nth indexOf – Juha Untinen Aug 27 '14 at 08:44
1

@JuhaUntinen recursion?? – Pravat Panda Sep 01 '14 at 18:24

score 1 · Answer 4 · answered May 18 '14 at 05:12

You can write a function to return array of occurrence positions, Java has String.regionMatches function which is quite handy

public static ArrayList<Integer> occurrencesPos(String str, String substr) {
    final boolean ignoreCase = true;
    int substrLength = substr.length();
    int strLength = str.length();

    ArrayList<Integer> occurrenceArr = new ArrayList<Integer>();

    for(int i = 0; i < strLength - substrLength + 1; i++) {
        if(str.regionMatches(ignoreCase, i, substr, 0, substrLength))  {
            occurrenceArr.add(i);
        }
    }
    return occurrenceArr;
}

score 1 · Answer 5 · answered Jan 20 '21 at 18:24

1

I hope I'm not late to the party.. Here is my answer. I like using Pattern/Matcher because it uses regex which should be more efficient. Yet, I think this answer could be enhanced:

    Matcher matcher = Pattern.compile("is").matcher("I think there is a smarter solution, isn't there?");
    int numOfOcurrences = 2;
    for(int i = 0; i < numOfOcurrences; i++) matcher.find();
    System.out.println("Index: " + matcher.start());

answered Jan 20 '21 at 18:24

Hasnaa Ibraheem

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Nice solution, I found. Thank you Hasnaa! – Hassan Jamil May 26 '21 at 14:01

score 1 · Answer 6 · answered May 31 '21 at 08:48

It seems to be a good party... I'm in:

public static int nthIndexOf(String str, String subStr, int count) {
    int ind = -1;
    while(count > 0) {
        ind = str.indexOf(subStr, ind + 1);
        if(ind == -1) return -1;
        count--;
    }
    return ind;
}

score 1 · Answer 7 · answered Jul 25 '22 at 14:06

Anyone who is looking for Nth occurance of string

    public class NthOccuranceExample {
    
    public static void main(String[] args) {
        String str1 = "helloworld good morning good evening good night";
        String str2 = "ing";
        int n = 2;
    
        int index = nthOccurrence(str1, str2, n);
        System.out.println("index of str2 in str1 at occurrence "+ n +" = "+ index);
    }
    
    public static int nthOccurrence(String str1, String str2, int n) {
    
        String tempStr = str1;
        int tempIndex = -1;
        int finalIndex = 0;
        for(int occurrence = 0; occurrence < n ; ++occurrence){
            tempIndex = tempStr.indexOf(str2);
            if(tempIndex==-1){
                finalIndex = 0;
                break;
            }
            tempStr = tempStr.substring(++tempIndex);
            finalIndex+=tempIndex;
        }
        return --finalIndex;
    }
}

score 0 · Answer 8 · answered Sep 26 '13 at 18:32

i think a loop can be used.

1 - check if the last index of substring is not the end of the main string.
2 - take a new substring from the last index of the substring to the last index of the main string and check if it contains the search string
3 - repeat the steps in a loop

score 0 · Answer 9 · answered Dec 20 '20 at 12:31

if you want to find index for more than 2 occurrence:

public static int ordinalIndexOf(String fullText,String subText,int pos){

    if(fullText.contains(subText)){
        if(pos <= 1){
            return fullText.indexOf(subText);
        }else{
            --pos;
            return fullText.indexOf(subText, ( ordinalIndexOf(fullText,subText,pos) + 1) );
        }
    }else{
        return -1;
    }

}

score 0 · Answer 10 · answered Mar 22 '23 at 16:13

You can get any occurrence of a substring in a string with a recursive method like this without any libraries:

import java.util.Arrays;

public class Test {
    public static void main(String[] args) {
        String word = "unrestfulness";
        String[] temp = new String[word.length()];
        for (char c : word.toCharArray()) {
            int count = (int) Arrays.stream(temp).filter(e -> e != null && e.contains(String.valueOf(c))).count();
            int index = getIndex(word, String.valueOf(c), count);
            System.out.println(c + " " + count + " " + index);
            temp[index] = String.valueOf(c);
        }
    
        System.out.println("result -> " + Arrays.toString(temp));
    }
    
    public static int getIndex(String word, String letter, int count) {
        return count == 0 ? word.indexOf(letter) : word.indexOf(letter, getIndex(word, letter, count - 1) + 1);
    }
}

Finding second occurrence of a substring in a string in Java

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