How to convert comma-separated String to List

Question

Is there any built-in method in Java which allows us to convert comma separated String to some container  e g array  List or Vector   Or do I need to write custom code for that  String commaSeparated    quot item1   item2   item3 quot   List lt String gt  items     method that converts above string into list

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There is no built-in method for this but you can simply use split   method in this   String commaSeparated    item1   item2   item3   ArrayList lt String gt  items    new  ArrayList lt String gt  Arrays asList commaSeparated split

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ArrayList lt HashMap lt String  String gt  gt  mListmain   new ArrayList lt HashMap lt String  String gt  gt      String marray    mListmain split

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You can first split them using String split       and then convert the returned String array to an ArrayList using Arrays asList array

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You can do it as follows   This removes white space and split by comma where you do not need to worry about white spaces        String myString   A  B  C  D          Remove whitespace and split by comma      List lt String gt  finalString  Arrays asList myString split    s    s           System out println finalString

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Convert comma separated String to List  List lt String gt  items   Arrays asList str split    s    s        The above code splits the string on a delimiter defined as  zero or more whitespace  a literal comma  zero or more whitespace which will place the words into the list and collapse any whitespace between the words and commas     Please note that this returns simply a wrapper on an array  you CANNOT for example  remove   from the resulting List   For an actual ArrayList you must further use new ArrayList lt String gt

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Here is another one for converting  CSV to ArrayList     String str  string with comma   ArrayList aList  new ArrayList Arrays asList str split         for int i 0 i lt aList size   i          System out println   -- gt   aList get i        Prints you     -- string       -- with       -- comma

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If a List is the end-goal as the OP stated  then already accepted answer is still the shortest and the best  However I want to provide alternatives using Java 8 Streams  that will give you more benefit if it is part of a pipeline for further processing   By wrapping the result of the  split function  a native array  into a stream and then converting to a list   List lt String gt  list     Stream of  a b c  split          collect Collectors toList       If it is important that the result is stored as an ArrayList as per the title from the OP  you can use a different Collector method   ArrayList lt String gt  list      Stream of  a b c  split          collect Collectors toCollection ArrayList lt String gt   new      Or by using the RegEx parsing api   ArrayList lt String gt  list      Pattern compile         splitAsStream  a b c      collect Collectors toCollection ArrayList lt String gt   new      Note that you could still consider to leave the list variable typed as List lt String gt  instead of ArrayList lt String gt   The generic interface for List still looks plenty of similar enough to the ArrayList implementation   By themselves  these code examples do not seem to add a lot  except more typing   but if you are planning to do more  like this answer on converting a String to a List of Longs exemplifies  the streaming API is really powerful by allowing to pipeline your operations one after the other    For the sake of  you know  completeness

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In groovy  you can use tokenize Character Token  method   list   str tokenize

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In Kotlin if your String list like this and you can use for convert string to ArrayList use this line of code  var str   item1  item2  item3  item4  var itemsList   str split

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List lt String gt  items  Stream of commaSeparated split             map String  trim        collect toList

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You can use Guava to split the string  and convert it into an ArrayList  This works with an empty string as well  and returns an empty list    import com google common base Splitter  import com google common collect Lists   String commaSeparated    item1   item2   item3       Split string into list  trimming each item and removing empty items ArrayList lt String gt  list   Lists newArrayList Splitter on      trimResults   omitEmptyStrings   splitToList commaSeparated    System out println list    list add  another item    System out println list     outputs the following    item1  item2  item3   item1  item2  item3  another item

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List commaseperated   new ArrayList    String mylist    item1   item2   item3   mylist   Arrays asList myStr trim   split              enter code here

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Arrays asList returns a fixed-size List backed by the array  If you want a normal mutable java util ArrayList you need to do this   List lt String gt  list   new ArrayList lt String gt  Arrays asList string split             Or  using Guava   List lt String gt  list   Lists newArrayList Splitter on        split string      Using a Splitter gives you more flexibility in how you split the string and gives you the ability to  for example  skip empty strings in the results and trim results  It also has less weird behavior than String split as well as not requiring you to split by regex  that s just one option

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String -  Collection conversion   String -  String   -  Collection              java version 8  String str    aa bb cc dd aa ss bb ee aa zz dd ff hh                Collection              Set   List          HashSet   ArrayList                                                                                                           Collection lt String gt  col   new HashSet lt  gt  Stream of str split       collect Collectors toList        Collection -  String   conversion   String   se   col toArray new String col size        String -  String   conversion   String   strArr   str split         And Collection -  Collection   List lt String gt  list   new LinkedList lt  gt  col

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convert Collection into string as comma seperated in Java 8  listOfString object contains   A   B   C    D   elements-  listOfString stream   map ele- gt     ele      collect Collectors joining         Output is  -  A   B   C   D   And Convert Strings Array to List in Java 8      String string      A   B   C   D        List lt String gt  listOfString   Stream of string  collect Collectors toList

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List lt String gt  items   Arrays asList s split      s

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An example using Collections   import java util Collections       String commaSeparated    item1   item2   item3   ArrayList lt String gt  items   new ArrayList lt  gt     Collections addAll items  commaSeparated split    s    s

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This code will help   String myStr    item1 item2 item3   List myList   Arrays asList myStr split

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While this question is old and has been answered multiple times  none of the answers is able to manage the all of the following cases    quot  quot  - gt  empty string should be mapped to empty list  quot  a  b   c  quot  - gt  all elements should be trimmed  including the first and last element  quot    quot  - gt  empty elements should be removed  Thus  I m using the following code  using org apache commons lang3 StringUtils  e g  https   mvnrepository com artifact org apache commons commons-lang3 3 11   StringUtils isBlank commaSeparatedEmailList                Collections emptyList                 Stream of StringUtils split commaSeparatedEmailList                             map String  trim                       filter StringUtils  isNotBlank                       collect Collectors toList      Using a simple split expression has an advantage  no regular expression is used  so the performance is probably higher  The commons-lang3 library is lightweight and very common  Note that the implementation assumes that you don t have list element containing comma  i e   quot a   b c   d quot  will be parsed as   quot a quot    quot  b quot    quot c  quot    quot d quot    not to   quot a quot    quot b c quot    quot d quot

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I usually use precompiled pattern for the list  And also this is slightly more universal since it can consider brackets which follows some of the listToString expressions   private static final Pattern listAsString   Pattern compile                             private List lt String gt  getList String value      Matcher matcher   listAsString matcher  String  value     if  matcher matches          String   split   matcher group matcher groupCount    split    s    s         return new ArrayList lt  gt  Arrays asList split          return Collections emptyList

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Two steps     String    items   commaSeparated split    s    s     List lt String gt  container   Arrays asList items

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you can combine asList and split  Arrays asList CommaSeparated split    s    s

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There are many ways to solve this using streams in Java 8 but IMO the following one liners are straight forward   String  commaSeparated    item1   item2   item3   List lt String gt  result1   Arrays stream commaSeparated split                                                       collect Collectors toList     List lt String gt  result2   Stream of commaSeparated split                                                       collect Collectors toList

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Same result you can achieve using the Splitter class   var list   Splitter on      splitToList YourStringVariable     written in kotlin

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List lt String gt  items   Arrays asList commaSeparated split          That should work for you

[java] How to convert comma-separated String to List?

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