Trim characters in Java

Question

How can I trim characters in Java  e g    String j       joe jill     Trim new char                 j should be       joe jill    String j      jack joe jill     Trim  jack      j should be        joe jill     etc

User · Answer

My solution  private static String trim String string  String charSequence            var str   string          str   str replace  quot   quot    quot  SAVE SPACE  quot                      replace charSequence   quot   quot                      trim                      replace  quot   quot   charSequence                     replace  quot  SAVE SPACE  quot    quot   quot            return str

User · Answer

CharMatcher     Google Guava  In the past  I d second Colins    Apache commons-lang answer  But now that Google   s guava-libraries is released  the CharMatcher class will do what you want quite nicely   String j   CharMatcher is       trimFrom    joe  jill          j is now joe jill   CharMatcher has a very simple and powerful set of APIs as well as some predefined constants which make manipulation very easy  For example   CharMatcher is      countIn  a b c       returns 2 CharMatcher isNot      countIn  a b c       returns 3 CharMatcher inRange  a    b   countIn  a b c       returns 2 CharMatcher DIGIT retainFrom  a12b34       returns  1234  CharMatcher ASCII negate   removeFrom  a    b       returns  ab     Very nice stuff

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public static String trim String value  char c         if  c  lt   32  return value trim         int len   value length        int st   0      char   val   value toCharArray          avoid getfield opcode         while   st  lt  len   amp  amp   val st     c             st              while   st  lt  len   amp  amp   val len - 1     c             len--            return   st  gt  0      len  lt  value length       value substring st  len    value

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Hand made for the first option    public class Rep       public static void main  String    args            System out println  trimChar                joe  jill                        System out println  trimChar          joe  jill                   private static String trimChar  char toTrim  String inString              int from   0          int to   inString length             for  int i   0   i  lt  inString length     i                   if  inString charAt  i      toTrim                    from   i                  break                                  for  int i   inString length  -1   i  gt   0   i--                 if  inString charAt  i      toTrim                    to   i                  break                                  return inString substring  from   to              Prints  joe jil  joe jil

User · Answer

This does what you want   public static void main  String   args        String a      joe  jill         String b   a replaceAll              replaceAll                   System out println b       The   is used to remove the sequence in the end of string  The   is used to remove in the beggining    As an alternative  you can use the syntax   String b   a replaceAll                       The   means  or    In case you want to trim other chars  just adapt the regex   String b   a replaceAll  y   x           will remove all the y from the end and x from the beggining

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Here is another non-regexp  non-super-awesome  non-super-optimized  however very easy to understand non-external-lib solution   public static String trimStringByString String text  String trimBy        int beginIndex   0      int endIndex   text length         while  text substring beginIndex  endIndex  startsWith trimBy             beginIndex    trimBy length                while  text substring beginIndex  endIndex  endsWith trimBy             endIndex -  trimBy length               return text substring beginIndex  endIndex       Usage   String trimmedString   trimStringByString stringToTrim

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10 year old question but felt most of the answers were a bit convoluted or didn t quite work the way that was asked  Also the most upvoted answer here didn t provide any examples  Here s a simple class I made   https   gist github com Maxdw d71afd11db2df4f1297ad3722d6392ec  Usage   Trim left   joe jill             joe jill    Trim left  jack joe jill     jack        joe jill    Trim left      joe  jill                joe  jill

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it appears that there is no ready to use java api that makes that but you can write a method to do that for you  this link might be usefull

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Apache Commons has a great StringUtils class  org apache commons lang StringUtils   In StringUtils there is a strip String  String  method that will do what you want   I highly recommend using Apache Commons anyway  especially the Collections and Lang libraries

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I don t think there is any built in function to trim based on a passed in string    Here is a small example of how to do this    This is not likely the most efficient solution  but it is probably fast enough for most situations  evaluate and adapt to your needs   I recommend testing performance and optimizing as needed for any code snippet that will be used regularly    Below  I ve included some timing information as an example    public String trim  String stringToTrim  String stringToRemove         String answer   stringToTrim       while  answer startsWith  stringToRemove                   answer   answer substring  stringToRemove length                 while  answer endsWith  stringToRemove                   answer   answer substring  0  answer length   - stringToRemove length                 return answer      This answer assumes that the characters to be trimmed are a string   For example  passing in  abc  will trim out  abc  but not  bbc  or  cba   etc   Some performance times for running each of the following 10 million times     mile   trim    runs in 248 ms included as a reference implementation for performance comparisons   trim   smiles    s     runs in 547 ms - approximately 2 times as long as java s String trim   method    smiles  replaceAll  s   s       runs in 12 306 ms - approximately 48 times as long as java s String trim   method   And using a compiled regex pattern Pattern pattern   Pattern compile  s   s    pattern matcher  smiles   replaceAll      runs in 7 804 ms - approximately 31 times as long as java s String trim   method

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Here s how I would do it   I think it s about as efficient as it reasonably can be   It optimizes the single character case and avoids creating multiple substrings for each subsequence removed   Note that the corner case of passing an empty string to trim is handled  some of the other answers would go into an infinite loop        Trim all occurrences of the string  lt code gt rmvval lt  code gt  from the left and right of  lt code gt src lt  code gt    Note that  lt code gt rmvval lt  code gt  constitutes an entire string which must match using  lt code gt String startsWith lt  code gt  and  lt code gt String endsWith lt  code gt      static public String trim String src  String rmvval        return trim src rmvval rmvval true              Trim all occurrences of the string  lt code gt lftval lt  code gt  from the left and  lt code gt rgtval lt  code gt  from the right of  lt code gt src lt  code gt    Note that the values to remove constitute strings which must match using  lt code gt String startsWith lt  code gt  and  lt code gt String endsWith lt  code gt      static public String trim String src  String lftval  String rgtval  boolean igncas        int                                 str 0 end src length         if lftval length    1                                                          optimize for common use - trimming a single character from left         char chr lftval charAt 0           while str lt end  amp  amp  src charAt str   chr    str                    else if lftval length   gt 1                                                      handle repeated removal of a specific character sequence from left         int vallen lftval length   newstr          while  newstr  str vallen   lt  end  amp  amp  src regionMatches igncas str lftval 0 vallen     str newstr                   if rgtval length    1                                                          optimize for common use - trimming a single character from right         char chr rgtval charAt 0           while str lt end  amp  amp  src charAt end-1   chr    end--                  else if rgtval length   gt 1                                                      handle repeated removal of a specific character sequence from right         int vallen rgtval length   newend          while str lt   newend  end-vallen    amp  amp  src regionMatches igncas newend rgtval 0 vallen     end newend                   if str  0    end  src length              if str lt end    src src substring str end                                   str is inclusive  end is exclusive         else          src                                          return src

User · Answer

I would actually write my own little function that does the trick by using plain old char access   public static String trimBackslash  String str         int len  left  right      return str    null      len   str length        0                                    left   str charAt  0             1   0                  right   len  gt  left  amp  amp  str charAt  len - 1             1   0        0           str   str substring  left  len - right        This behaves similar to what String trim   does  only that it works with     instead of space   Here is one alternative that works and actually uses trim       Althogh it s not very efficient it will probably beat all regexp based approaches performance wise   String j       joe jill      j   j replace          f    trim   replace    f

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You could use removeStart and removeEnd from Apache Commons Lang StringUtils

User · Answer

EDIT  Amended by answer to replace just the first and last     character   System err println    joe  jill    replaceAll

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