Java Tutorial/Regular Expressions/Validation

Date format consists of one or two digits followed by a hyphen, followed by one or two digits, followed by a hypen, followed by four digits

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String date = "12-12-1212";
   String datePattern = "\\d{1,2}-\\d{1,2}-\\d{4}";
   System.out.println(date.matches(datePattern));
 }

}</source>

Finding duplication of words

   <source lang="java">

import java.util.regex.Matcher; import java.util.regex.Pattern; import java.util.regex.PatternSyntaxException; public class MainClass {

 public static void main(String args[]) {
   String phrase = "a word word";
   String duplicatePattern = "\\b(\\w+) \\1\\b";
   Pattern p = null;
   try {
     p = Pattern.rupile(duplicatePattern);
   } catch (PatternSyntaxException pex) {
     pex.printStackTrace();
     System.exit(0);
   }
   // count the number of matches.
   int matches = 0;
   // get the matcher
   Matcher m = p.matcher(phrase);
   String val = null;
   // find all matching Strings
   while (m.find()) {
     val = ":" + m.group() + ":";
     System.out.println(val);
     matches++;
   }
 }

}</source>

Match a digit

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String candidate = "Java 6";
   String pattern = "Java \\d";
   System.out.println(candidate.matches(pattern));
 }

}</source>

Name validation

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String name = "First Name";
   String nameToken = "\\p{Upper}(\\p{Lower}+\\s?)";
   String namePattern = "(" + nameToken + "){2,3}";
   System.out.println(name.matches(namePattern));
 }

}</source>

Phone number validation

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String phone = "123-(456)-9999";
   String phoneNumberPattern = "(\\d-)?(\\d{3}-)?\\d{3}-\\d{4}";
   System.out.println(phone.matches(phoneNumberPattern));
 }

}</source>

Primitive address validation

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String addr = "my Address 12345";
   String namePattern = "([A-Za-z])+ (([A-Za-z])+\\.? )?([A-Za-z])+\\s*";
   String zipCodePattern = "\\d{5}(-\\d{4})?";
   String addressPattern = "^" + namePattern + "\\w+ .*, \\w+ " + zipCodePattern + "$";
   System.out.println(addr.matches(addressPattern));
 }

}</source>

String manipulation using English synonyms

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String statement = "A B AA";
   String tokens[] = null;
   String splitPattern = "A|B|C|E|(G H I J)|(AA BB CC)";
   tokens = statement.split(splitPattern);
   System.out.println("REGEX PATTERN:\n" + splitPattern + "\n");
   System.out.println("STATEMENT:\n" + statement + "\n");
   System.out.println("TOKENS:");
   for (int i = 0; i < tokens.length; i++) {
     System.out.println(tokens[i]);
   }
 }

}</source>

Zip code validation

   <source lang="java">

public class MainClass {

 public static void main(String args[]) {
   String zip = "123456";
   String zipCodePattern = "\\d{5}(-\\d{4})?";
   System.out.println(zip.matches(zipCodePattern));
 }

}</source>