Split a string, at every nth position

by

For a big performance improvement, an alternative would be to use substring() in a loop:

public String[] splitStringEvery(String s, int interval) {
    int arrayLength = (int) Math.ceil(((s.length() / (double)interval)));
    String[] result = new String[arrayLength];

    int j = 0;
    int lastIndex = result.length - 1;
    for (int i = 0; i < lastIndex; i++) {
        result[i] = s.substring(j, j + interval);
        j += interval;
    } //Add the last bit
    result[lastIndex] = s.substring(j);

    return result;
}

Example:

Input:  String st = "1231241251341351452342352456"
Output: 123 124 125 134 135 145 234 235 245 6.

It’s not as short as stevevls’ solution, but it’s way more efficient (see below) and I think it would be easier to adjust in the future, of course depending on your situation.

Performance tests (Java 7u45)

2,000 characters long string – interval is 3.

split("(?<=\\G.{" + count + "})") performance (in miliseconds):

7, 7, 5, 5, 4, 3, 3, 2, 2, 2

splitStringEvery() (substring()) performance (in miliseconds):

2, 0, 0, 0, 0, 1, 0, 1, 0, 0

2,000,000 characters long string – interval is 3.

split() performance (in miliseconds):

207, 95, 376, 87, 97, 83, 83, 82, 81, 83

splitStringEvery() performance (in miliseconds):

44, 20, 13, 24, 13, 26, 12, 38, 12, 13

2,000,000 characters long string – interval is 30.

split() performance (in miliseconds):

103, 61, 41, 55, 43, 44, 49, 47, 47, 45

splitStringEvery() performance (in miliseconds):

7, 7, 2, 5, 1, 3, 4, 4, 2, 1

Conclusion:

The splitStringEvery() method is a lot faster (even after the changes in Java 7u6), and it escalates when the intervals become higher.

Ready-to-use Test Code:

pastebin.com/QMPgLbG9

More Related Contents:

  1. How to split a string if any chracter is found in java
  2. Split string to equal length substrings in Java
  3. Split string with dot as delimiter
  4. Splitting on comma outside quotes
  5. Java string split with “.” (dot) [duplicate]
  6. Splitting a string at every n-th character
  7. How to split String with some separator but without removing that separator in Java? [duplicate]
  8. Extracting pairs of words using String.split()
  9. Java String.split() Regex
  10. Java String.split() sometimes giving blank strings
  11. How to Split a mathematical expression on operators as delimiters, while keeping them in the result?
  12. Java split is eating my characters
  13. Split string into repeated characters
  14. Java replace all square brackets in a string
  15. Java String split removed empty values
  16. Regex to match a C-style multiline comment
  17. How to split a string in Java
  18. Java – Best way to grab ALL Strings between two Strings? (regex?)
  19. How do I convert CamelCase into human-readable names in Java?
  20. Check and extract a number from a String in Java
  21. What is the simplest way to convert a Java string from all caps (words separated by underscores) to CamelCase (no word separators)?
  22. Remove all empty lines
  23. Split the string on forward slash
  24. A method to reverse effect of java String.split()? [duplicate]
  25. Java split String performances
  26. Java String ReplaceAll method giving illegal repetition error?
  27. Find all words with 3 letters with regex
  28. Java equivalent to Explode and Implode(PHP) [closed]
  29. String.replaceAll is considerably slower than doing the job yourself
  30. Remove all occurrences of \ from string

Leave a Comment