Splitting a string at every n-th character

Question

In JavaScript this is how we can split a string at every 3-rd character   foobarspam  match    1 3  g    I am trying to figure out how to do this in Java  Any pointers

User · Answer

import java util ArrayList  import java util List   public class Test       public static void main String   args            for  String part   getParts  foobarspam   3                 System out println part                       private static List lt String gt  getParts String string  int partitionSize            List lt String gt  parts   new ArrayList lt String gt             int len   string length            for  int i 0  i lt len  i  partitionSize                        parts add string substring i  Math min len  i   partitionSize                       return parts

User · Answer

Late Entry   Following is a succinct implementation using Java8 streams  a one liner   String foobarspam    foobarspam   AtomicInteger splitCounter   new AtomicInteger 0   Collection lt String gt  splittedStrings   foobarspam                                      chars                                        mapToObj  char - gt  String valueOf  char  char                                        collect Collectors groupingBy stringChar - gt  splitCounter getAndIncrement     3                                                                  Collectors joining                                          values      Output    foo  bar  spa  m

User · Answer

You could do it like this   String s    1234567890   System out println java util Arrays toString s split     lt    G            which produces    123  456  789  0    The regex    lt   G     matches an empty string that has the last match   G  followed by three characters       before it     lt

User · Answer

Using plain java       String s    1234567890       List lt String gt  list   new Scanner s  findAll        map MatchResult  group  collect Collectors toList         System out printf   s n   list     Produces the output       123  456  789    Note that this discards leftover characters  0 in this case

User · Answer

You can also split a string at every n-th character and put them each  in each index of a List    Here I made a list of Strings named Sequence       List  lt  String   Sequence   Then I m basically splitting the String  KILOSO  by every 2 words  So  KI   LO   SO  would be incorporate in separate index of the List called Sequence        String S   KILOSO           Sequence   Arrays asList S split     lt   G              So when I m doing       System out print Sequence    It should print        KI  LO  SO    to verify I can write       System out print Sequence get 1     it will print       LO

User · Answer

As an addition to Bart Kiers answer I want to add that it is possible instead of using the three dots     in the regex expression which are representing three characters you can write   3  which has the same meaning   Then the code would look like the following   String bitstream    00101010001001010100101010100101010101001010100001010101010010101   System out println java util Arrays toString bitstream split     lt    G  3          With this it would be easier to modify the string length and the creation of a function is now reasonable with a variable input string length  This could be done look like the following   public static String   splitAfterNChars String input  int splitLen       return input split String format     lt    G   1 d     splitLen        An example in IdeOne  http   ideone com rNlTj5

User · Answer

Java does not provide very full-featured splitting utilities  so the Guava libraries do   Iterable lt String gt  pieces   Splitter fixedLength 3  split string     Check out the Javadoc for Splitter  it s very powerful

User · Answer

This a late answer  but I am putting it out there anyway for any new programmers to see   If  you do  not want to use regular expressions  and do not wish to  rely on a third party library  you can use this method instead  which takes between   89920 and 100113 nanoseconds in a 2 80 GHz CPU  less than a millisecond   It s not as pretty as Simon Nickerson s example  but it works                 Divides the given string into substrings each consisting of the provided        length s                   param string                   the string to split          param defaultLength                   the default length used for any extra substrings  If set to                    lt code gt 0 lt  code gt   the last substring will start at the sum of                    lt code gt lengths lt  code gt  and end at the end of  lt code gt string lt  code gt           param lengths                   the lengths of each substring in order  If any substring is not                   provided a length  it will use  lt code gt defaultLength lt  code gt           return the array of strings computed by splitting this string into the given                substring lengths              public static String   divideString String string  int defaultLength  int    lengths            java util ArrayList lt String gt  parts   new java util ArrayList lt String gt              if  lengths length    0                parts add string substring 0  defaultLength                string   string substring defaultLength               while  string length    gt  0                    if  string length    lt  defaultLength                        parts add string                       break                                    parts add string substring 0  defaultLength                    string   string substring defaultLength                           else               for  int i   0  temp  i  lt  lengths length  i                      temp   lengths i                   if  string length    lt  temp                        parts add string                       break                                    parts add string substring 0  temp                    string   string substring temp                             while  string length    gt  0                    if  string length    lt  defaultLength    defaultLength  lt   0                        parts add string                       break                                    parts add string substring 0  defaultLength                    string   string substring defaultLength                                    return parts toArray new String parts size

User · Answer

I recently encountered this issue  and here is the solution I came up with  final int LENGTH   10  String test    Here is a very long description  it is going to be past 10    Map lt Integer StringBuilder gt  stringBuilderMap   new HashMap lt  gt     for   int i   0  i  lt  test length    i           int position   i   LENGTH     i lt 10 then 0  10 lt  i lt 19 then 1  20 lt  i lt 30 then 2  etc       StringBuilder currentSb   stringBuilderMap computeIfAbsent  position  pos - gt  new StringBuilder         find sb  or create one if not present     currentSb append  test charAt  i         add the current char to our sb    List lt String gt  comments   stringBuilderMap entrySet   stream            sorted  Comparator comparing  Map Entry  getKey              map  entrySet - gt  entrySet getValue   toString              collect  Collectors toList        done       here you can see the data comments forEach  cmt - gt  System out println  String format     s      length   d   cmt  cmt length             PRINTS      Here is a       length  10     very long       length  10     descriptio      length  10     n  it is g      length  10     oing to be      length  10      past 10      length  8     make sure they are equal String joinedString   String join      comments    System out println    nOriginal strings are equal     joinedString equals  test         PRINTS  Original strings are equal true

[java] Splitting a string at every n-th character

Examples related to java

Examples related to regex

Examples related to string

Examples related to split