String contains - ignore case

Question

Is it possible to determine if a String str1  ABCDEFGHIJKLMNOP  contains a string pattern strptrn  gHi   I wanted to know if that s possible when the characters are case insensitive  If so  how

User · Answer

If you won t go with regex    ABCDEFGHIJKLMNOP  toLowerCase   contains  gHi  toLowerCase

User · Answer

Try this  public static void main String   args         String original    ABCDEFGHIJKLMNOPQ       String tobeChecked    GHi        System out println containsString original  tobeChecked  true                System out println containsString original  tobeChecked  false        public static boolean containsString String original  String tobeChecked  boolean caseSensitive        if  caseSensitive                return original contains tobeChecked              else               return original toLowerCase   contains tobeChecked toLowerCase

User · Answer

You can use java util regex Pattern with the CASE INSENSITIVE flag for case insensitive matching   Pattern compile Pattern quote strptrn   Pattern CASE INSENSITIVE  matcher str1  find

User · Answer

You can use  org apache commons lang3 StringUtils containsIgnoreCase CharSequence str                                       CharSequence searchStr        Checks if CharSequence contains a search CharSequence irrespective of   case  handling null  Case-insensitivity is defined as by   String equalsIgnoreCase String        A null CharSequence will return false    This one will be better than regex as regex is always expensive in terms of performance   For official doc  refer to   StringUtils containsIgnoreCase  Update    If you are among the ones who    don t want to use Apache commons library don t want to go with the expensive regex Pattern based solutions   don t want to create additional string object by using toLowerCase     you can implement your own custom containsIgnoreCase using java lang String regionMatches  public boolean regionMatches boolean ignoreCase                               int toffset                               String other                               int ooffset                               int len    ignoreCase   if true  ignores case when comparing characters   public static boolean containsIgnoreCase String str  String searchStr            if str    null    searchStr    null  return false       final int length   searchStr length        if  length    0          return true       for  int i   str length   - length  i  gt   0  i--            if  str regionMatches true  i  searchStr  0  length               return true            return false

User · Answer

An optimized Imran Tariq s version  Pattern compile strptrn  Pattern CASE INSENSITIVE   Pattern LITERAL  matcher str1  find      Pattern quote strptrn  always returns   Q    s     E  even if there is nothing to quote  concatination spoils performance

[java] String contains - ignore case

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