Java how to replace 2 or more spaces with single space in string and delete leading and trailing spaces

Question

Looking for quick  simple way in Java to change this string     hello     there       to something that looks like this   hello there    where I replace all those multiple spaces with a single space  except I also want the one or more spaces at the beginning of string to be gone   Something like this gets me partly there  String mytext     hello     there      mytext   mytext replaceAll                 but not quite

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I know replaceAll method is much easier but I wanted to post this as well   public static String removeExtraSpace String input        input  input trim        ArrayList  lt String gt  x  new ArrayList lt  gt  Arrays asList input split            for int i 0  i lt x size  -1 i              if x get i  equals       amp  amp  x get i 1  equals                      x remove i                i--                       String word         for String each  x           word  each      return word

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String str     hello world    reduce spaces first   str   str trim   replaceAll               capitalize the first letter and lowercase everything else  str   str substring 0 1  toUpperCase    str substring 1 str length    toLowerCase

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This worked for me  scan  filter scan       s           scan  sac trim      where filter is following function and scan is the input string   public String filter String scan  String regex  String replace        StringBuffer sb   new StringBuffer         Pattern pt   Pattern compile regex       Matcher m   pt matcher scan        while  m find              m appendReplacement sb  replace              m appendTail sb        return sb toString

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See String replaceAll   Use the regex   s  and replace with       Then use String trim

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The simplest method for removing white space anywhere in the string    public String removeWhiteSpaces String returnString       returnString   returnString trim   replaceAll                           return returnString

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String blogName    quot how to   do    in  java             com quot      String nameWithProperSpacing   blogName replaceAll  quot    s  quot    quot   quot

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public class RemoveExtraSpacesEfficient        public static void main String   args             String s    my    name is    mr    space             char   charArray   s toCharArray             char prev   s charAt 0            for  int i   0  i  lt  charArray length  i                  char cur   charArray i               if  cur         amp  amp  prev                          else                   System out print cur                             prev   cur                      The above solution is the algorithm with the complexity of O n  without using any java function

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You just need a   replaceAll    s 2          trim      where you match one or more spaces and replace them with a single space and then trim whitespaces at the beginning and end  you could actually invert by first trimming and then matching to make the regex quicker as someone pointed out    To test this out quickly try   System out println new String   hello     there      trim   replaceAll    s 2              and it will return     hello there

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String myText       Hello     World      myText   myText trim   replace          g           Output   Hello World

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You can first use String trim    and then apply the regex replace command on the result

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String str      this is string      str   str replaceAll    s         trim

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Hello sorry for the delay   Here is the best and the most efficiency answer that you are looking for   import java util regex Matcher  import java util regex Pattern   public class MyPatternReplace    public String replaceWithPattern String str String replace        Pattern ptn   Pattern compile    s         Matcher mtch   ptn matcher str       return mtch replaceAll replace      public static void main String a         String str    My    name    is  kingkon          MyPatternReplace mpr   new MyPatternReplace        System out println mpr replaceWithPattern str             So your output of this example will be  My name is kingkon     However this method will remove also the   n  that your string may has  So if you do not want that just use this simple method   while  str contains            2 spaces str   str replace                2 spaces  1 space       And if you want to strip the leading and trailing spaces too just add   str   str trim

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To eliminate spaces at the beginning and at the end of the String  use String trim   method  And then use your mytext replaceAll

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Try this one   Sample Code  String str     hello     there      System out println str replaceAll             trim       OUTPUT  hello there   First it will replace all the spaces with single space  Than we have to supposed to do trim String because Starting of the String and End of the String it will replace the all space with single space if String has spaces at Starting of the String and End of the String So we need to trim them  Than you get your desired String

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In Kotlin it would look like this  val input     n n n  a     string with     many    spaces      n  val cleanedInput   input trim   replace Regex     s

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2      This will match more than one space   String mytext     hello     there        without trim - gt    hello there    with trim - gt   hello there  mytext   mytext trim   replaceAll      2           System out println mytext     OUTPUT   hello there

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You could use lookarounds also   test replaceAll             lt               OR  test replaceAll                          lt space gt       matches a space character which is followed by another space character  So in consecutive spaces  it would match all the spaces except the last because it isn t followed by a space character  This leaving you a single space for consecutive spaces after the removal operation     Example       String   tests                    x                  x                 1   2   3          1 2 3                                                                                             for  String test   tests                System out format    s  n                   test replaceAll

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My method before I found the second answer using regex as a better solution  Maybe someone needs this code   private String replaceMultipleSpacesFromString String s       if s length      0   return          int timesSpace   0      String res            for  int i   0  i  lt  s length    i              char c   s charAt i            if c                      timesSpace                if timesSpace  lt  2                  res    c           else              res    c              timesSpace   0                       return res trim

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check this     public static void main String   args        String s    A B  C   D    E F      G tH I rJ nK tL       System out println  Current          s       System out println  Single Space     singleSpace s        System out println  Space  count     spaceCount s        System out format  Replace  all    s   s replaceAll    s                  Example where it uses the most      String s    My name is yashwanth   M       String s2    My nameis yashwanth M        System out println  Normal      s equals s2        System out println  Replace     s replaceAll    s        equals s2 replaceAll    s                 If String contains only single-space then replace   will not-replace    If spaces are more than one  Then replace   action performs and removes spacess   public static String singleSpace String str       return str replaceAll            t  r  n           To count the number of spaces in a String   public static String spaceCount String str       int i   0      while str indexOf       gt  -1           str   str replaceFirst          i              str   str replaceFirst Pattern quote           i                 return str      Pattern quote      returns literal pattern String

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Please use below code  package com myjava string   import java util StringTokenizer   public class MyStrRemoveMultSpaces        public static void main String a              String str    String    With Multiple      Spaces            StringTokenizer st   new StringTokenizer str                 StringBuffer sb   new StringBuffer             while st hasMoreElements                 sb append st nextElement    append                          System out println sb toString   trim

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Use the Apache commons StringUtils normalizeSpace String str  method  See docs here

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Try this   String after   before trim   replaceAll               See also   String trim     Returns a copy of the string  with leading and trailing whitespace omitted   regular-expressions info Repetition     No trim   regex  It s also possible to do this with just one replaceAll  but this is much less readable than the trim   solution  Nonetheless  it s provided here just to show what regex can do       String   tests                x                  x             1   2   3          1 2 3                                                                             for  String test   tests            System out format    s  n               test replaceAll                   1                      There are 3 alternates          any sequence of spaces at the beginning of the string   Match and replace with  1  which captures the empty string        any sequence of spaces at the end of the string   Match and replace with  1  which captures the empty string         any sequence of spaces that matches none of the above  meaning it s in the middle   Match and replace with  1  which captures a single space    See also   regular-expressions info Anchors

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you should do it like this  String mytext     hello     there      mytext   mytext replaceAll                 put   inside round brackets

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trim   Removes only the leading  amp  trailing spaces  From Java Doc   quot Returns a string whose value is this string  with any leading and trailing whitespace removed  quot  System out println  quot  D ev  Dum my  quot  trim       quot D ev  Dum my quot  replace    replaceAll   Replaces all the empty strings in the word  System out println  quot  D ev  Dum my  quot  replace  quot   quot   quot  quot      System out println  quot  D ev  Dum my  quot  replaceAll  quot   quot   quot  quot      System out println  quot  D ev  Dum my  quot  replaceAll  quot   s  quot   quot  quot      Output   quot DevDummy quot    quot DevDummy quot    quot DevDummy quot   Note   quot  s  quot  is the regular expression similar to the empty space character  Reference   https   www codedjava com 2018 06 replace-all-spaces-in-string-trim html

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String Tokenizer can be used    String str      hello    there                 StringTokenizer stknzr   new StringTokenizer str                    StringBuffer sb   new StringBuffer                while stknzr hasMoreElements                                  sb append stknzr nextElement    append                                 System out println sb toString   trim

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trim   method removes the leading and trailing spaces and using replaceAll  quot regex quot    quot string to replace quot   method with regex  quot  s  quot  matches more than one space and will replace it with a single space myText   myText trim   replaceAll  quot   s  quot   quot   quot

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Stream version  filters spaces and tabs   Stream of str split      t     filter s - gt  s length    gt  0  collect Collectors joining

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This worked perfectly for me   sValue   sValue trim   replaceAll    s

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A lot of correct answers been provided so far and I see lot of upvotes  However  the mentioned ways will work but not really optimized or not really readable  I recently came across the solution which every developer will like   String nameWithProperSpacing   StringUtils normalizeSpace  stringWithLotOfSpaces      You are done  This is readable solution

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The following code will compact any whitespace between words and remove any at the string s beginning and end  String input     n n n  a     string with     many    spaces      n                    a  t tab and a newline n n   String output   input trim   replaceAll    s          System out println output     This will output a string with many spaces  a tab and a newline  Note that any non-printable characters including spaces  tabs and newlines will be compacted or removed    For more information see the respective documentation    String trim   method String replaceAll String regex  String replacement  method For information about Java s regular expression implementation see the documentation of the Pattern class

[java] Java how to replace 2 or more spaces with single space in string and delete leading and trailing spaces

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