How to match letters only using java regex matches method

Question

import java util regex Pattern   class HowEasy       public boolean matches String regex            System out println Pattern matches regex   abcABC                return Pattern matches regex   abcABC               public static void main String   args            HowEasy words   new HowEasy            words matches   a-zA-Z               The output is False  Where am I going wrong  Also I want to check if a word contains only letters and may or maynot end with a single period  What is the regex for that   i e  abc   abc   is valid but  abc    is not valid    I can use indexOf   method to solve it  but I want to know if it is possible to use a single regex

User · Answer

Three problems here    Just use String matches   - if the API is there  use it In java  matches  means  matches the entire input   which IMHO is counter-intuitive  so let your method s API reflect that by letting callers think about matching part of the input as your example suggests You regex matches only 1 character   I recommend you use code like this   public boolean matches String regex        regex           regex             pad with regex to allow partial matching     System out println  abcABC     matches regex        return  abcABC     matches regex      public static void main String   args        HowEasy words   new HowEasy        words matches   a-zA-Z         added      ie 1-to-n of  to character class

User · Answer

matches method performs matching of full line  i e  it is equivalent to find   with   abc    So  just use Pattern compile   a-zA-Z    matcher str  find   instead  Then fix your regex  As  user unknown mentioned your regex actually matches only one character  You probably should say  a-zA-Z

User · Answer

A-Za-z    to match letters and spaces

User · Answer

import java io BufferedReader  import java io IOException  import java io InputStreamReader  import java util regex        Write an application that prompts the user for a String that contains at least    five letters and at least five digits  Continuously re-prompt the user until a    valid String is entered  Display a message indicating whether the user was    successful or did not enter enough digits  letters  or both      public class FiveLettersAndDigits      private static String readIn        read input from stdin     StringBuilder sb   new StringBuilder        int c   0      try      do not use try-with-resources  We don t want to close the stdin stream       BufferedReader reader   new BufferedReader new InputStreamReader System in          while   c   reader read       0       read all characters until null            We don t want new lines  although we must consume them          if  c    13  amp  amp  c    10              sb append  char  c             else             break     break on new line  or else the loop won t terminate                             reader readLine       get the trailing new line       catch  IOException ex          System err println  Failed to read user input           ex printStackTrace System err              return sb toString   trim                    Check the given input against a pattern            return the number of matches         private static int getitemCount String input  String pattern        int count   0       try         Pattern p   Pattern compile pattern         Matcher m   p matcher input         while  m find         count the number of times the pattern matches         count                  catch  PatternSyntaxException ex          System err println  Failed to test input String       input       for matches to pattern       pattern                 ex printStackTrace System err              return count         private static String reprompt         System out print  Entered input is invalid  Please enter five letters and five digits in any order           String in   readIn         return in         public static void main String   args        int letters   0  digits   0      String in   null      System out print  Please enter five letters and five digits in any order          in   readIn        while  letters  lt  5    digits  lt  5       will keep occuring until the user enters sufficient input       if  null    in  amp  amp  in length    gt  9       must be at least 10 chars long in order to contain both            count the letters and numbers  If there are enough  this loop won t happen again          letters   getitemCount in    A-Za-z             digits   getitemCount in    0-9              if  letters  lt  5    digits  lt  5              in   reprompt       reset in case we need to go around again                    else           in   reprompt

User · Answer

a-zA-Z   matches only one character  To match multiple characters  use   a-zA-Z      Since a dot is a joker for any character  you have to mask it   abc    To make the dot optional  you need a question mark   abc       If you write the Pattern as literal constant in your code  you have to mask the backslash   System out println   abc  matches   abc         System out println   abc   matches   abc         System out println   abc    matches   abc           Combining both patterns   System out println   abc   matches    a-zA-Z             Instead of a-zA-Z   w is often more appropriate  since it captures foreign characters like            and so on   System out println   abc   matches     w

[java] How to match letters only using java regex, matches method?

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