Regular expression

[Chris Bro]

Hi all,

I am not verry good in regular expressions and try to remove the character which looks like a square or a rectangle form a String. But I really do not know how to do that. I know that since JDK 1.4 regular expressions are in the package but how do I express this character? It is a non ASCII character and I am not able to paste it here.
I have to send this String using SOAP and during the data encryption the server crashes.
Is there a way to remove all non ASCII characters from a String or has someone
an other adivce?

Thanks in advance

Chris

[Tong Chen]

try this:

^[-\w`~!@#$%^&*\(\)+={}|\[\]\\:";'<>?,.\/ ]*$

This makes sure string only contains characters that appear on keyboard. Extended characters (such as those with ascii values above 127), will not pass the test.

[Chris Bro]

Hi Tong,

first thank you for your fast reply. Could you please give me a little example how to embed this in Java? As I mentioned I never done this in Java before and unfortunately it is very urgent.

Thanks

Chris

[somkiat puisungnoen]

What are regular expressions?

A regular expression, also known as a regex or regexp, is a string whose pattern (template) describes a set of strings. The pattern determines what strings belong to the set, and consists of literal characters and metacharacters, characters that have special meaning instead of a literal meaning. The process of searching text to identify matches�strings that match a regex's pattern�is pattern matching.

Java's java.util.regex package supports pattern matching via its Pattern, Matcher, and PatternSyntaxException classes:


Pattern objects, also known as patterns, are compiled regexes

Matcher objects, or matchers, are engines that interpret patterns to locate matches in character sequences, objects whose classes implement the java.lang.CharSequence interface and serve as text sources

PatternSyntaxException objects describe illegal regex patterns


Code example

 
import java.util.regex.*;
 
class RegexDemo
{
   public static void main (String [] args)
   {
      if (args.length != 2)
      {
          System.err.println ("java RegexDemo regex text");
          return;
      }
 
      Pattern p;
      try
      {
         p = Pattern.compile (args [0]);
      }
      catch (PatternSyntaxException e)
      {
         System.err.println ("Regex syntax error: " + e.getMessage ());
         System.err.println ("Error description: " + e.getDescription ());
         System.err.println ("Error index: " + e.getIndex ());
         System.err.println ("Erroneous pattern: " + e.getPattern ());
         return;
      }
 
      String s = cvtLineTerminators (args [1]);
      Matcher m = p.matcher (s);
 
      System.out.println ("Regex = " + args [0]);
      System.out.println ("Text = " + s);
      System.out.println ();
      while (m.find ())
      {
         System.out.println ("Found " + m.group ());
         System.out.println ("  starting at index " + m.start () +
                             " and ending at index " + m.end ());
         System.out.println ();
      }
   }
 
   // Convert \n and \r character sequences to their single character
   // equivalents
 
   static String cvtLineTerminators (String s)
   {
      StringBuffer sb = new StringBuffer (80);
 
      int oldindex = 0, newindex;
      while ((newindex = s.indexOf ("\\n", oldindex)) != -1)
      {
         sb.append (s.substring (oldindex, newindex));
         oldindex = newindex + 2;
         sb.append ('\n');
      }
      sb.append (s.substring (oldindex));
 
      s = sb.toString ();
 
      sb = new StringBuffer (80);
 
      oldindex = 0;
      while ((newindex = s.indexOf ("\\r", oldindex)) != -1)
      {
         sb.append (s.substring (oldindex, newindex));
         oldindex = newindex + 2;
         sb.append ('\r');
      }
      sb.append (s.substring (oldindex));
 
      return sb.toString ();
   }
}
 

 

Run
java RegexDemo apple applet


Result

Regex = apple
Text = applet

Found apple
starting at index 0 and ending at index 5