Sorting arraylist in alphabetical order case insensitive

Question

I have a string arraylist names which contains names of people  I want to sort the arraylist in alphabetical order   ArrayList lt String gt  names   new ArrayList lt String gt     names add  seetha    names add  sudhin    names add  Swetha    names add  Neethu    names add  ananya    names add  Athira    names add  bala    names add  Tony    names add  Karthika    names add  Nithin    names add  Vinod    names add  jeena    Collections sort names   for int i 0  i lt names size    i        System out println names get i      I tried to sort the list in above way  But it is displaying the sorted array as   Athira Karthika       ananya bala       but I don t want to make it case sensitive  I want the result as   ananya Athira bala

User · Answer

def  lst     quot A2 quot    quot A1 quot    quot k22 quot    quot A6 quot    quot a3 quot    quot a5 quot    quot A4 quot    quot A7 quot      println lst sort   a  b - gt  a compareToIgnoreCase b    This should be able to sort with case insensitive but I am not sure how to tackle the alphanumeric strings lists

User · Answer

Unfortunately  all answers so far do not take into account that  a  must not be considered equal to  A  when it comes to sorting    String   array     b    A    C    B    a        Approach 1 Arrays sort array      array is  A  B  C  a  b      Approach 2 Arrays sort array  String CASE INSENSITIVE ORDER      array is  A  a  b  B  C      Approach 3 Arrays sort array  java text Collator getInstance        array is  a  A  b  B  C    In approach 1 any lower case letters are considered greater than any upper case letters   Approach 2 makes it worse  since CASE INSENSITIVE ORDER considers  a  and  A  equal  comparation result is 0   This makes sorting non-deterministic   Approach 3  using a java text Collator  is IMHO the only way of doing it correctly  since it considers  a and  A  not equal  but puts them in the correct order according to the current  or any other desired  Locale

User · Answer

try this code  Collections sort yourarraylist  new SortBasedOnName        import java util Comparator  import com RealHelp objects FBFriends Obj  import com RealHelp ui importFBContacts   public class SortBasedOnName implements Comparator   public int compare Object o1  Object o2          FBFriends Obj dd1    FBFriends Obj o1    where FBFriends Obj is your object class     FBFriends Obj dd2    FBFriends Obj o2      return dd1 uname compareToIgnoreCase dd2 uname    where uname is field name

User · Answer

The simplest thing to do is   Collections sort list  String CASE INSENSITIVE ORDER

User · Answer

KOTLIN DEVELOPERS For Custome List  if you want to sort based on one String then you can use this  phoneContactArrayList sortWith Comparator   item  t1 - gt          val s1  String   item phoneContactUserName         val s2  String   t1 phoneContactUserName         s1 compareTo s2  ignoreCase   true

User · Answer

Based on the above mentioned answers  I managed to compare my custom Class Objects like this   ArrayList lt Item gt  itemList   new ArrayList lt  gt         Collections sort itemList  new Comparator lt Item gt                   Override             public int compare Item item  Item t1                    String s1   item getTitle                    String s2   t1 getTitle                    return s1 compareToIgnoreCase s2

User · Answer

Custom Comparator should help  Collections sort list  new Comparator lt String gt           Override     public int compare String s1  String s2            return s1 compareToIgnoreCase s2               Or if you are using Java 8   list sort String  compareToIgnoreCase

User · Answer

Starting from Java 8 you can use Stream   List lt String gt  sorted   Arrays asList                            names stream   sorted                                 s1  s2  - gt  s1 compareToIgnoreCase s2                              toArray String    new                             It gets a stream from that ArrayList  then it sorts it  ignoring the case   After that  the stream is converted to an array which is converted to an ArrayList   If you print the result using   System out println sorted     you get the following output    ananya  Athira  bala  jeena  Karthika  Neethu  Nithin  seetha  sudhin  Swetha  Tony  Vinod

User · Answer

You need to use custom comparator which will use compareToIgnoreCase  not compareTo

[java] Sorting arraylist in alphabetical order (case insensitive)

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