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

User · Answer

int first   string indexOf  is    int second   string indexOf  is   first   1     This overload starts looking for the substring from the given index

User · Answer

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  quot is quot   matcher  quot I think there is a smarter solution  isn t there  quot        int numOfOcurrences   2      for int i   0  i  lt  numOfOcurrences  i    matcher find        System out println  quot Index   quot    matcher start

User · Answer

Use overloaded version of indexOf    which takes the starting index   fromIndex  as 2nd parameter   str indexOf  is   str indexOf  is     1

User · Answer

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  lt   1               return fullText indexOf subText            else              --pos              return fullText indexOf subText    ordinalIndexOf fullText subText pos    1                    else          return -1

User · Answer

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

User · Answer

I am using   Apache Commons Lang  StringUtils ordinalIndexOf    StringUtils ordinalIndexOf  Java Language    a   2

User · Answer

You can write a function to return array of occurrence positions  Java has String regionMatches function which is quite handy  public static ArrayList lt Integer gt  occurrencesPos String str  String substr        final boolean ignoreCase   true      int substrLength   substr length        int strLength   str length         ArrayList lt Integer gt  occurrenceArr   new ArrayList lt Integer gt          for int i   0  i  lt  strLength - substrLength   1  i              if str regionMatches ignoreCase  i  substr  0  substrLength                  occurrenceArr add i                       return occurrenceArr

[java] Finding second occurrence of a substring in a string in Java

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