Java/Regular Expressions/Validation

Find duplication

 
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
public class MatchDuplicateWords {
  public static void main(String args[]) {
    hasDuplicate("pizza pizza");
    hasDuplicate("Faster pussycat kill kill");
    hasDuplicate("The mayor of of simpleton");
    hasDuplicate("Never Never Never Never Never");
    hasDuplicate("222 2222");
    hasDuplicate("sara sarah");
    hasDuplicate("Faster pussycat kill, kill");
    hasDuplicate(". .");
  }
  public static boolean hasDuplicate(String phrase) {
    boolean retval = false;
    String duplicatePattern = "\\b(\\w+) \\1\\b";
    Pattern p = null;
    try {
      p = Pattern.rupile(duplicatePattern);
    } catch (PatternSyntaxException pex) {
      pex.printStackTrace();
      System.exit(0);
    }
    int matches = 0;
    Matcher m = p.matcher(phrase);
    String val = null;
    while (m.find()) {
      retval = true;
      val = ":" + m.group() + ":";
      System.out.println(val);
      matches++;
    }
    String msg = "   NO MATCH: pattern:" + phrase
        + "\r\n             regex: " + duplicatePattern;
    if (retval) {
      msg = " MATCH     : pattern:" + phrase + "\r\n         regex: "
          + duplicatePattern;
    }
    System.out.println(msg + "\r\n");
    return retval;
  }
}

Perform credit card validations.

 
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

/**
 * <p>Perform credit card validations.</p>
 * <p>
 * By default, all supported card types are allowed.  You can specify which 
 * cards should pass validation by configuring the validation options.  For 
 * example,<br/><code>CreditCardValidator ccv = new CreditCardValidator(CreditCardValidator.AMEX + CreditCardValidator.VISA);</code>
 * configures the validator to only pass American Express and Visa cards.
 * If a card type is not directly supported by this class, you can implement
 * the CreditCardType interface and pass an instance into the 
 * <code>addAllowedCardType</code> method.
 * </p>
 * For a similar implementation in Perl, reference Sean M. Burke"s
 * .
 *
 * @version $Revision: 478334 $ $Date: 2006-11-22 21:31:54 +0000 (Wed, 22 Nov 2006) $
 * @since Validator 1.1
 */
public class CreditCardValidator {
    /**
     * Option specifying that no cards are allowed.  This is useful if
     * you want only custom card types to validate so you turn off the
     * default cards with this option.
     * <br/>
     * <pre>
     * CreditCardValidator v = new CreditCardValidator(CreditCardValidator.NONE);
     * v.addAllowedCardType(customType);
     * v.isValid(aCardNumber);
     * </pre>
     * @since Validator 1.1.2
     */
    public static final int NONE = 0;
    /**
     * Option specifying that American Express cards are allowed.
     */
    public static final int AMEX = 1 << 0;
    /**
     * Option specifying that Visa cards are allowed.
     */
    public static final int VISA = 1 << 1;
    /**
     * Option specifying that Mastercard cards are allowed.
     */
    public static final int MASTERCARD = 1 << 2;
    /**
     * Option specifying that Discover cards are allowed.
     */
    public static final int DISCOVER = 1 << 3;
    
    /**
     * The CreditCardTypes that are allowed to pass validation.
     */
    private Collection cardTypes = new ArrayList();
    /**
     * Create a new CreditCardValidator with default options.
     */
    public CreditCardValidator() {
        this(AMEX + VISA + MASTERCARD + DISCOVER);
    }
    /**
     * Create a new CreditCardValidator with the specified options.
     * @param options Pass in
     * CreditCardValidator.VISA + CreditCardValidator.AMEX to specify that 
     * those are the only valid card types.
     */
    public CreditCardValidator(int options) {
        super();
        Flags f = new Flags(options);
        if (f.isOn(VISA)) {
            this.cardTypes.add(new Visa());
        }
        if (f.isOn(AMEX)) {
            this.cardTypes.add(new Amex());
        }
        if (f.isOn(MASTERCARD)) {
            this.cardTypes.add(new Mastercard());
        }
        if (f.isOn(DISCOVER)) {
            this.cardTypes.add(new Discover());
        }
    }
    /**
     * Checks if the field is a valid credit card number.
     * @param card The card number to validate.
     * @return Whether the card number is valid.
     */
    public boolean isValid(String card) {
        if ((card == null) || (card.length() < 13) || (card.length() > 19)) {
            return false;
        }
        if (!this.luhnCheck(card)) {
            return false;
        }
        
        Iterator types = this.cardTypes.iterator();
        while (types.hasNext()) {
            CreditCardType type = (CreditCardType) types.next();
            if (type.matches(card)) {
                return true;
            }
        }
        return false;
    }
    
    /**
     * Add an allowed CreditCardType that participates in the card 
     * validation algorithm.
     * @param type The type that is now allowed to pass validation.
     * @since Validator 1.1.2
     */
    public void addAllowedCardType(CreditCardType type){
        this.cardTypes.add(type);
    }
    /**
     * Checks for a valid credit card number.
     * @param cardNumber Credit Card Number.
     * @return Whether the card number passes the luhnCheck.
     */
    protected boolean luhnCheck(String cardNumber) {
        // number must be validated as 0..9 numeric first!!
        int digits = cardNumber.length();
        int oddOrEven = digits & 1;
        long sum = 0;
        for (int count = 0; count < digits; count++) {
            int digit = 0;
            try {
                digit = Integer.parseInt(cardNumber.charAt(count) + "");
            } catch(NumberFormatException e) {
                return false;
            }
            if (((count & 1) ^ oddOrEven) == 0) { // not
                digit *= 2;
                if (digit > 9) {
                    digit -= 9;
                }
            }
            sum += digit;
        }
        return (sum == 0) ? false : (sum % 10 == 0);
    }
    
    /**
     * CreditCardType implementations define how validation is performed
     * for one type/brand of credit card.
     * @since Validator 1.1.2
     */
    public interface CreditCardType {
        
        /**
         * Returns true if the card number matches this type of credit
         * card.  Note that this method is <strong>not</strong> responsible
         * for analyzing the general form of the card number because 
         * <code>CreditCardValidator</code> performs those checks before 
         * calling this method.  It is generally only required to valid the
         * length and prefix of the number to determine if it"s the correct 
         * type. 
         * @param card The card number, never null.
         * @return true if the number matches.
         */
        boolean matches(String card);
        
    }
    
    /**
     *  Change to support Visa Carte Blue used in France
     *  has been removed - see Bug 35926
     */
    private class Visa implements CreditCardType {
        private static final String PREFIX = "4";
        public boolean matches(String card) {
            return (
                card.substring(0, 1).equals(PREFIX)
                    && (card.length() == 13 || card.length() == 16));
        }
    }
            
    private class Amex implements CreditCardType {
        private static final String PREFIX = "34,37,";
        public boolean matches(String card) {
            String prefix2 = card.substring(0, 2) + ",";
            return ((PREFIX.indexOf(prefix2) != -1) && (card.length() == 15));
        }
    }
    
    private class Discover implements CreditCardType {
        private static final String PREFIX = "6011";
        public boolean matches(String card) {
            return (card.substring(0, 4).equals(PREFIX) && (card.length() == 16));
        }
    }
    
    private class Mastercard implements CreditCardType {
        private static final String PREFIX = "51,52,53,54,55,";
        public boolean matches(String card) {
            String prefix2 = card.substring(0, 2) + ",";
            return ((PREFIX.indexOf(prefix2) != -1) && (card.length() == 16));
        }
    }
}

/**
 * Represents a collection of 64 boolean (on/off) flags.  Individual flags 
 * are represented by powers of 2.  For example,<br/>
 * Flag 1 = 1<br/>
 * Flag 2 = 2<br/>
 * Flag 3 = 4<br/>
 * Flag 4 = 8<br/><br/>
 * or using shift operator to make numbering easier:<br/>
 * Flag 1 = 1 &lt;&lt; 0<br/>
 * Flag 2 = 1 &lt;&lt; 1<br/>
 * Flag 3 = 1 &lt;&lt; 2<br/>
 * Flag 4 = 1 &lt;&lt; 3<br/>
 * 
 * <p>
 * There cannot be a flag with a value of 3 because that represents Flag 1 
 * and Flag 2 both being on/true.
 * </p>
 *
 * @version $Revision: 478334 $ $Date: 2006-11-22 21:31:54 +0000 (Wed, 22 Nov 2006) $
 */
class Flags implements Serializable {
    /**
     * Represents the current flag state.
     */
    private long flags = 0;
    /**
     * Create a new Flags object.
     */
    public Flags() {
        super();
    }
    /**
     * Initialize a new Flags object with the given flags.
     *
     * @param flags collection of boolean flags to represent.
     */
    public Flags(long flags) {
        super();
        this.flags = flags;
    }
    /**
     * Returns the current flags.
     *
     * @return collection of boolean flags represented.
     */
    public long getFlags() {
        return this.flags;
    }
    /**
     * Tests whether the given flag is on.  If the flag is not a power of 2 
     * (ie. 3) this tests whether the combination of flags is on.
     *
     * @param flag Flag value to check.
     *
     * @return whether the specified flag value is on.
     */
    public boolean isOn(long flag) {
        return (this.flags & flag) > 0;
    }
    /**
     * Tests whether the given flag is off.  If the flag is not a power of 2 
     * (ie. 3) this tests whether the combination of flags is off.
     *
     * @param flag Flag value to check.
     *
     * @return whether the specified flag value is off.
     */
    public boolean isOff(long flag) {
        return (this.flags & flag) == 0;
    }
    /**
     * Turns on the given flag.  If the flag is not a power of 2 (ie. 3) this
     * turns on multiple flags.
     *
     * @param flag Flag value to turn on.
     */
    public void turnOn(long flag) {
        this.flags |= flag;
    }
    /**
     * Turns off the given flag.  If the flag is not a power of 2 (ie. 3) this
     * turns off multiple flags.
     *
     * @param flag Flag value to turn off.
     */
    public void turnOff(long flag) {
        this.flags &= ~flag;
    }
    /**
     * Turn off all flags.
     */
    public void turnOffAll() {
        this.flags = 0;
    }
    
    /**
     * Turn off all flags.  This is a synonym for <code>turnOffAll()</code>.
     * @since Validator 1.1.1
     */
    public void clear() {
        this.flags = 0;
    }
    /**
     * Turn on all 64 flags.
     */
    public void turnOnAll() {
        this.flags = Long.MAX_VALUE;
    }
    /**
     * Clone this Flags object.
     *
     * @return a copy of this object.
     * @see java.lang.Object#clone()
     */
    public Object clone() {
        try {
            return super.clone();
        } catch(CloneNotSupportedException e) {
            throw new RuntimeException("Couldn"t clone Flags object.");
        }
    }
    /**
     * Tests if two Flags objects are in the same state.
     * @param obj object being tested
     * @see java.lang.Object#equals(java.lang.Object)
     *
     * @return whether the objects are equal.
     */
    public boolean equals(Object obj) {
        if (!(obj instanceof Flags)) {
            return false;
        }
        if (obj == this) {
            return true;
        }
        Flags f = (Flags) obj;
        return this.flags == f.flags;
    }
    /**
     * The hash code is based on the current state of the flags.
     * @see java.lang.Object#hashCode()
     *
     * @return the hash code for this object.
     */
    public int hashCode() {
        return (int) this.flags;
    }
    /**
     * Returns a 64 length String with the first flag on the right and the 
     * 64th flag on the left.  A 1 indicates the flag is on, a 0 means it"s 
     * off.
     *
     * @return string representation of this object.
     */
    public String toString() {
        StringBuffer bin = new StringBuffer(Long.toBinaryString(this.flags));
        for (int i = 64 - bin.length(); i > 0; i--) {
            bin.insert(0, "0");
        }
        return bin.toString();
    }
}

Simplest validation

 
public class ValidationTest {
  public static void main(String[] args) {
    String candidate = "I love Java and jexp";
    String pattern = "Java \\d";
    System.out.println(candidate.matches(pattern));
  }
}

Validation with Pattern and Matcher

 
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
public class ValidationTestWithPatternAndMatcher {
  public static void main(String args[]) {
    Pattern p = null;
    try {
      p = Pattern.rupile("Java \\d");
    } catch (PatternSyntaxException pex) {
      pex.printStackTrace();
      System.exit(0);
    }
    String candidate = "I love Java 5";
    Matcher m = p.matcher(candidate);
    System.out.println("result=" + m.find());
  }
}