Option to ignore case with contains method

Question

Is there an option to ignore case with  contains   method   I have an ArrayList of DVD object  Each DVD object has a few elements  one of them is a title  And I have a method that searches for a specific title  It works  but I d like it to be case insensitive

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You can t guarantee that you re always going to get String objects back  or that the object you re working with in the List implements a way to ignore case   If you do want to compare Strings in a collection to something independent of case  you d want to iterate over the collection and compare them without case   String word    Some word   List lt String gt  aList   new ArrayList lt  gt        presume that the list is populated  for String item   aList        if word equalsIgnoreCase item                operation upon successful match

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private List lt String gt  FindString String stringToLookFor  List lt String gt  arrayToSearchIn          List lt String gt  ReceptacleOfWordsFound   new ArrayList lt String gt           if  arrayToSearchIn isEmpty                    for String lCurrentString   arrayToSearchIn                          if lCurrentString toUpperCase   contains stringToLookFor toUpperCase                     ReceptacleOfWordsFound add lCurrentString                       return ReceptacleOfWordsFound

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If you re using Java 8  List lt String gt  list   new ArrayList lt  gt      boolean containsSearchStr   list stream   anyMatch  search value   equalsIgnoreCase

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In Java 8 you can use the Stream interface   return dvdList stream   anyMatch d - gt  d getTitle   equalsIgnoreCase  SomeTitle

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This probably isn t the best way for your particular problem  but you can use the String matches String regex  method or the matcher equivalent   We just need to construct a regular expression from your prospective title   Here it gets complex   List lt DVD gt  matchingDvds String titleFragment        String escapedFragment   Pattern quote titleFragment          The pattern may have contained an asterisk  dollar sign  etc         For example  M A S H  directed by Robert Altman      Pattern pat   Pattern compile escapedFragment  Pattern CASE INSENSITIVE       List lt DVD gt  foundDvds   new ArrayList lt  gt         for  DVD dvd  catalog            Matcher m   pat matcher dvd getTitle             if  m find                  foundDvds add dvd                       return foundDvds      But this is inefficient  and it s being done purely in Java  You would do better to try one of these techniques    Learn the Collator and CollationKey classes  If you have no choice but to stay in the Java world  add a method to DVD  boolean matches String fragment   Have the DVD tell you what it matches  Use a database   If it supports case-insensitive collations  declare the title column of the DVD table that way   Use JDBC or Hibernate or JPA or Spring Data  whichever you choose  If the database supports advanced text search  like Oracle  use that  Back in the Java world  use Apache Lucene and possibly Apache Solr  Use a language tuned for case-insensitive matches    If you can wait until Java 8  use lambda expressions   You can avoid the Pattern and Matcher class that I used above by building the regex this way      String escapedFragment   Pattern quote titleFragment      String fragmentAnywhereInString          escapedFragment            String caseInsensitiveFragment      i     fragmentAnywhereInString        and in the loop  use     if dvd getTitle   matches caseInsensitiveFragment             foundDvds add dvd           But this compiles the pattern too many times   What about lower-casing everything   if  dvd getTitle   toLowerCase   contains titleFragment toLowerCase       Congratulations  you ve just discovered the Turkish problem   Unless you state the locale in toLowerCase   Java finds the current locale   And the lower-casing is slow because it has to take into account the Turkish dotless i and dotted I   At least you have no patterns and no matchers

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The intuitive solution to transform both operands to lower case  or upper case  has the effect of instantiating an extra String object for each item which is not efficient for large collections  Also  regular expressions are an order of magnitude slower than simple characters comparison   String regionMatches   allows to compare two String regions in a case-insensitive way  Using it  it s possible to write an efficient version of a case-insensitive  contains  method  The following method is what I use  it s based on code from Apache commons-lang   public static boolean containsIgnoreCase final String str  final String searchStr        if  str    null    searchStr    null            return false            final int len   searchStr length        final int max   str length   - len      for  int i   0  i  lt   max  i              if  str regionMatches true  i  searchStr  0  len                 return true                      return false

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You can apply little trick over this   Change all the string to same case  either upper or lower case  For C  Code   List searchResults   sl FindAll s    s ToUpper   Contains seachKeyword ToUpper       For Java Code   import java util      class Test       public static void main String   args                String itemCheck  check           ArrayList lt String gt  listItem  new ArrayList lt String gt             listItem add  Check            listItem add  check            listItem add  CHeck            listItem add  Make            listItem add  CHecK            for String item  listItem                        if item toUpperCase   equals itemCheck toUpperCase                                   System out println item

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If you are looking for contains  amp  not equals then i would propose below solution  Only drawback is if your searchItem in below solution is  DE  then also it would match      List lt String gt  list   new ArrayList lt  gt         public static final String   LIST OF ELEMENTS      ABC    DEF   GHI         String searchItem   def         if String join      LIST OF ELEMENTS  contains searchItem toUpperCase                   System out println  found element                break

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I m guessing you mean ignoring case when searching in a string   I don t know any  but you could try to convert the string to search into either to lower or to upper case  then search      s is the String to search into  and seq the sequence you are searching for  bool doesContain   s toLowerCase   contains seq     Edit  As Ryan Schipper suggested  you can also  and probably would be better off  do seq toLowerCase    depending on your situation

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I know I m a little late to the party but in Kotlin you can easily use  fun Collection lt String gt  containsIgnoreCase item  String    any       it equals item  ignoreCase   true      val list   listOf  quot Banana quot    println list contains  quot banana quot    println list containsIgnoreCase  quot BaNaNa quot

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For Java 8  You can have one more solution like below   List lt String gt  list   new ArrayList lt  gt     String searchTerm    dvd    if String join      list  toLowerCase   contains searchTerm       System out println  Element Present

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With a null check on the dvdList and your searchString     if   StringUtils isEmpty searchString             return Optional ofNullable dvdList                          map Collection  stream                          orElse Stream empty                            anyMatch dvd  gt searchString equalsIgnoreCase dvd getTitle

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private boolean containsIgnoreCase List lt String gt  list  String soughtFor        for  String current   list            if  current equalsIgnoreCase soughtFor                 return true                      return false

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Kotlin Devs  go with any   none  private fun compareCategory          categories  List lt String gt            category  String         categories  any   it equals category  true       false

[java] Option to ignore case with .contains method?

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