Hello Bruno, when building commons-text I get:
testGetJaroWinklerDistance_StringString(org.apache.commons.text.similarity.TestJaroWrinklerDistance) Time elapsed: 0.015 sec <<< FAILURE! java.lang.AssertionError: expected:<0.93> but was:<0.02> at org.junit.Assert.fail(Assert.java:88) at org.junit.Assert.failNotEquals(Assert.java:743) at org.junit.Assert.assertEquals(Assert.java:494) at org.junit.Assert.assertEquals(Assert.java:592) at org.apache.commons.text.similarity.TestJaroWrinklerDistance.testGetJaroWinklerDistance_StringString(TestJaroWrinklerDistance.java:38) Running org.apache.commons.text.similarity.TestLevenshteinDistance Tests run: 7, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.006 sec - in org.apache.commons.text.similarity.TestLevenshteinDistance Results : Failed tests: TestJaroWrinklerDistance.testGetJaroWinklerDistance_StringString:38 expected:<0.93> but was:<0.02> Tests run: 16, Failures: 1, Errors: 0, Skipped: 0 can you check? thanks! Benedikt 2014-11-20 5:54 GMT+01:00 <ki...@apache.org>: > Repository: commons-text > Updated Branches: > refs/heads/master 71b59af90 -> c0e8c0210 > > > SANDBOX-483 Incorporate String algorithms from Commons Lang > > > Project: http://git-wip-us.apache.org/repos/asf/commons-text/repo > Commit: > http://git-wip-us.apache.org/repos/asf/commons-text/commit/c0e8c021 > Tree: http://git-wip-us.apache.org/repos/asf/commons-text/tree/c0e8c021 > Diff: http://git-wip-us.apache.org/repos/asf/commons-text/diff/c0e8c021 > > Branch: refs/heads/master > Commit: c0e8c021059d8300f90cf2123528a35d7c468b57 > Parents: 71b59af > Author: Bruno P. Kinoshita <brunodepau...@yahoo.com.br> > Authored: Thu Nov 20 02:23:05 2014 -0200 > Committer: Bruno P. Kinoshita <brunodepau...@yahoo.com.br> > Committed: Thu Nov 20 02:23:05 2014 -0200 > > ---------------------------------------------------------------------- > .../commons/text/similarity/FuzzyDistance.java | 130 +++++++ > .../text/similarity/JaroWrinklerDistance.java | 373 +++++++++++++++++++ > .../text/similarity/LevenshteinDistance.java | 258 +++++++++++++ > .../commons/text/similarity/StringMetric.java | 45 +++ > .../commons/text/similarity/package-info.java | 22 ++ > .../text/similarity/TestFuzzyDistance.java | 75 ++++ > .../similarity/TestJaroWrinklerDistance.java | 62 +++ > .../similarity/TestLevenshteinDistance.java | 146 ++++++++ > 8 files changed, 1111 insertions(+) > ---------------------------------------------------------------------- > > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/main/java/org/apache/commons/text/similarity/FuzzyDistance.java > ---------------------------------------------------------------------- > diff --git > a/src/main/java/org/apache/commons/text/similarity/FuzzyDistance.java > b/src/main/java/org/apache/commons/text/similarity/FuzzyDistance.java > new file mode 100644 > index 0000000..8e9228a > --- /dev/null > +++ b/src/main/java/org/apache/commons/text/similarity/FuzzyDistance.java > @@ -0,0 +1,130 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +import java.util.Locale; > + > +/** > + * <p> > + * This string matching algorithm is similar to the algorithms of editors > such > + * as Sublime Text, TextMate, Atom and others. One point is given for > every > + * matched character. Subsequent matches yield two bonus points. A higher > score > + * indicates a higher similarity. > + * </p> > + * > + * @since 1.0 > + */ > +public class FuzzyDistance implements StringMetric<Integer> { > + > + /** > + * <p> > + * Find the Fuzzy Distance which indicates the similarity score > between two > + * Strings. This method uses the default locale. > + * </p> > + * > + * @param term a full term that should be matched against, must not > be null > + * @param query the query that will be matched against a term, must > not be > + * null > + * @return result score > + * @throws IllegalArgumentException if either String input {@code > null} > + */ > + @Override > + public Integer compare(CharSequence term, CharSequence query) { > + return compare(term, query, Locale.getDefault()); > + } > + > + /** > + * <p> > + * Find the Fuzzy Distance which indicates the similarity score > between two > + * Strings. > + * </p> > + * > + * <pre> > + * StringUtils.getFuzzyDistance(null, null, null) > = IllegalArgumentException > + * StringUtils.getFuzzyDistance("", "", Locale.ENGLISH) > = 0 > + * StringUtils.getFuzzyDistance("Workshop", "b", Locale.ENGLISH) > = 0 > + * StringUtils.getFuzzyDistance("Room", "o", Locale.ENGLISH) > = 1 > + * StringUtils.getFuzzyDistance("Workshop", "w", Locale.ENGLISH) > = 1 > + * StringUtils.getFuzzyDistance("Workshop", "ws", Locale.ENGLISH) > = 2 > + * StringUtils.getFuzzyDistance("Workshop", "wo", Locale.ENGLISH) > = 4 > + * StringUtils.getFuzzyDistance("Apache Software Foundation", "asf", > Locale.ENGLISH) = 3 > + * </pre> > + * > + * @param term a full term that should be matched against, must not > be null > + * @param query the query that will be matched against a term, must > not be > + * null > + * @param locale This string matching logic is case insensitive. A > locale is > + * necessary to normalize both Strings to lower case. > + * @return result score > + * @throws IllegalArgumentException if either String input {@code > null} or > + * Locale input {@code null} > + */ > + public Integer compare(CharSequence term, CharSequence query, Locale > locale) { > + if (term == null || query == null) { > + throw new IllegalArgumentException("Strings must not be > null"); > + } else if (locale == null) { > + throw new IllegalArgumentException("Locale must not be null"); > + } > + > + // fuzzy logic is case insensitive. We normalize the Strings to > lower > + // case right from the start. Turning characters to lower case > + // via Character.toLowerCase(char) is unfortunately insufficient > + // as it does not accept a locale. > + final String termLowerCase = term.toString().toLowerCase(locale); > + final String queryLowerCase = > query.toString().toLowerCase(locale); > + > + // the resulting score > + int score = 0; > + > + // the position in the term which will be scanned next for > potential > + // query character matches > + int termIndex = 0; > + > + // index of the previously matched character in the term > + int previousMatchingCharacterIndex = Integer.MIN_VALUE; > + > + for (int queryIndex = 0; queryIndex < queryLowerCase.length(); > queryIndex++) { > + final char queryChar = queryLowerCase.charAt(queryIndex); > + > + boolean termCharacterMatchFound = false; > + for (; termIndex < termLowerCase.length() > + && !termCharacterMatchFound; termIndex++) { > + final char termChar = termLowerCase.charAt(termIndex); > + > + if (queryChar == termChar) { > + // simple character matches result in one point > + score++; > + > + // subsequent character matches further improve > + // the score. > + if (previousMatchingCharacterIndex + 1 == termIndex) { > + score += 2; > + } > + > + previousMatchingCharacterIndex = termIndex; > + > + // we can leave the nested loop. Every character in > the > + // query can match at most one character in the term. > + termCharacterMatchFound = true; > + } > + } > + } > + > + return score; > + } > + > +} > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/main/java/org/apache/commons/text/similarity/JaroWrinklerDistance.java > ---------------------------------------------------------------------- > diff --git > a/src/main/java/org/apache/commons/text/similarity/JaroWrinklerDistance.java > b/src/main/java/org/apache/commons/text/similarity/JaroWrinklerDistance.java > new file mode 100644 > index 0000000..2dcd51c > --- /dev/null > +++ > b/src/main/java/org/apache/commons/text/similarity/JaroWrinklerDistance.java > @@ -0,0 +1,373 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +/** > + * <p> > + * The Jaro measure is the weighted sum of percentage of matched > characters > + * from each file and transposed characters. Winkler increased this > measure > + * for matching initial characters. > + * </p> > + * > + * <p> > + * This implementation is based on the Jaro Winkler similarity algorithm > + * from <a href=" > http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance";> > + * http://en.wikipedia.org/wiki/Jaro%E2%80%93Winkler_distance</a>. > + * </p> > + * > + * <p> > + * This code has been adapted from Apache Commons Lang 3.3. > + * </p> > + * > + * @since 1.0 > + */ > +public class JaroWrinklerDistance implements StringMetric<Double> { > + > + /** > + * Represents a failed index search. > + */ > + public static final int INDEX_NOT_FOUND = -1; > + > + /** > + * <p> > + * Find the Jaro Winkler Distance which indicates the similarity score > + * between two Strings. > + * </p> > + * > + * <pre> > + * StringUtils.getJaroWinklerDistance(null, null) = > IllegalArgumentException > + * StringUtils.getJaroWinklerDistance("","") = 0.0 > + * StringUtils.getJaroWinklerDistance("","a") = 0.0 > + * StringUtils.getJaroWinklerDistance("aaapppp", "") = 0.0 > + * StringUtils.getJaroWinklerDistance("frog", "fog") = 0.93 > + * StringUtils.getJaroWinklerDistance("fly", "ant") = 0.0 > + * StringUtils.getJaroWinklerDistance("elephant", "hippo") = 0.44 > + * StringUtils.getJaroWinklerDistance("hippo", "elephant") = 0.44 > + * StringUtils.getJaroWinklerDistance("hippo", "zzzzzzzz") = 0.0 > + * StringUtils.getJaroWinklerDistance("hello", "hallo") = 0.88 > + * StringUtils.getJaroWinklerDistance("ABC Corporation", "ABC Corp") > = 0.91 > + * StringUtils.getJaroWinklerDistance("D N H Enterprises Inc", "D > & H Enterprises, Inc.") = 0.93 > + * StringUtils.getJaroWinklerDistance("My Gym Children's Fitness > Center", "My Gym. Childrens Fitness") = 0.94 > + * StringUtils.getJaroWinklerDistance("PENNSYLVANIA", > "PENNCISYLVNIA") = 0.9 > + * </pre> > + * > + * @param left the first String, must not be null > + * @param right the second String, must not be null > + * @return result distance > + * @throws IllegalArgumentException if either String input {@code > null} > + */ > + @Override > + public Double compare(CharSequence left, CharSequence right) { > + final double DEFAULT_SCALING_FACTOR = 0.1; > + > + if (left == null || right == null) { > + throw new IllegalArgumentException("Strings must not be > null"); > + } > + > + final double jaro = score(left, right); > + final int cl = commonPrefixLength(left, right); > + final double matchScore = Math.round(jaro + > (DEFAULT_SCALING_FACTOR > + * cl * (1.0 - jaro)) * 100.0) / 100.0; > + > + return matchScore; > + } > + > + // TODO: we can move these methods to a Util class, keep them here, > + // create a common abstract class, shade lang-3.3... > + > + /** > + * Calculates the number of characters from the beginning of the > strings > + * that match exactly one-to-one, up to a maximum of four (4) > characters. > + * > + * @param first The first string. > + * @param second The second string. > + * @return A number between 0 and 4. > + */ > + private static int commonPrefixLength(final CharSequence first, > + final CharSequence second) { > + final int result = getCommonPrefix(first.toString(), > second.toString()) > + .length(); > + > + // Limit the result to 4. > + return result > 4 ? 4 : result; > + } > + > + /** > + * <p> > + * Compares all Strings in an array and returns the initial sequence > of > + * characters that is common to all of them. > + * </p> > + * > + * <p> > + * For example, > + * <code>getCommonPrefix(new String[] {"i am a machine", "i am a > robot"}) -> "i am a "</code> > + * </p> > + * > + * <pre> > + * StringUtils.getCommonPrefix(null) = "" > + * StringUtils.getCommonPrefix(new String[] {}) = "" > + * StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc" > + * StringUtils.getCommonPrefix(new String[] {null, null}) = "" > + * StringUtils.getCommonPrefix(new String[] {"", ""}) = "" > + * StringUtils.getCommonPrefix(new String[] {"", null}) = "" > + * StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = "" > + * StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = "" > + * StringUtils.getCommonPrefix(new String[] {"", "abc"}) = "" > + * StringUtils.getCommonPrefix(new String[] {"abc", ""}) = "" > + * StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc" > + * StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a" > + * StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab" > + * StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab" > + * StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = "" > + * StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = "" > + * StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am > a robot"}) = "i am a " > + * </pre> > + * > + * @param strs array of String objects, entries may be null > + * @return the initial sequence of characters that are common to all > Strings > + * in the array; empty String if the array is null, the > elements are > + * all null or if there is no common prefix. > + * @since 2.4 > + */ > + public static String getCommonPrefix(final String... strs) { > + if (strs == null || strs.length == 0) { > + return ""; > + } > + final int smallestIndexOfDiff = indexOfDifference(strs); > + if (smallestIndexOfDiff == INDEX_NOT_FOUND) { > + // all strings were identical > + if (strs[0] == null) { > + return ""; > + } > + return strs[0]; > + } else if (smallestIndexOfDiff == 0) { > + // there were no common initial characters > + return ""; > + } else { > + // we found a common initial character sequence > + return strs[0].substring(0, smallestIndexOfDiff); > + } > + } > + > + /** > + * This method returns the Jaro-Winkler score for string matching. > + * > + * @param first the first string to be matched > + * @param second the second string to be machted > + * @return matching score without scaling factor impact > + */ > + protected static double score(final CharSequence first, > + final CharSequence second) { > + String shorter; > + String longer; > + > + // Determine which String is longer. > + if (first.length() > second.length()) { > + longer = first.toString().toLowerCase(); > + shorter = second.toString().toLowerCase(); > + } else { > + longer = second.toString().toLowerCase(); > + shorter = first.toString().toLowerCase(); > + } > + > + // Calculate the half length() distance of the shorter String. > + final int halflength = shorter.length() / 2 + 1; > + > + // Find the set of matching characters between the shorter and > longer > + // strings. Note that > + // the set of matching characters may be different depending on > the > + // order of the strings. > + final String m1 = getSetOfMatchingCharacterWithin(shorter, longer, > + halflength); > + final String m2 = getSetOfMatchingCharacterWithin(longer, shorter, > + halflength); > + > + // If one or both of the sets of common characters is empty, then > + // there is no similarity between the two strings. > + if (m1.length() == 0 || m2.length() == 0) { > + return 0.0; > + } > + > + // If the set of common characters is not the same size, then > + // there is no similarity between the two strings, either. > + if (m1.length() != m2.length()) { > + return 0.0; > + } > + > + // Calculate the number of transposition between the two sets > + // of common characters. > + final int transpositions = transpositions(m1, m2); > + > + // Calculate the distance. > + final double dist = (m1.length() / ((double) shorter.length()) > + + m2.length() / ((double) longer.length()) + (m1.length() > - transpositions) > + / ((double) m1.length())) / 3.0; > + return dist; > + } > + > + /** > + * Calculates the number of transposition between two strings. > + * > + * @param first The first string. > + * @param second The second string. > + * @return The number of transposition between the two strings. > + */ > + protected static int transpositions(final CharSequence first, > + final CharSequence second) { > + int transpositions = 0; > + for (int i = 0; i < first.length(); i++) { > + if (first.charAt(i) != second.charAt(i)) { > + transpositions++; > + } > + } > + return transpositions / 2; > + } > + > + /** > + * <p> > + * Compares all CharSequences in an array and returns the index at > which the > + * CharSequences begin to differ. > + * </p> > + * > + * <p> > + * For example, > + * <code>indexOfDifference(new String[] {"i am a machine", "i am a > robot"}) -> 7</code> > + * </p> > + * > + * <pre> > + * StringUtils.indexOfDifference(null) = -1 > + * StringUtils.indexOfDifference(new String[] {}) = -1 > + * StringUtils.indexOfDifference(new String[] {"abc"}) = -1 > + * StringUtils.indexOfDifference(new String[] {null, null}) = -1 > + * StringUtils.indexOfDifference(new String[] {"", ""}) = -1 > + * StringUtils.indexOfDifference(new String[] {"", null}) = 0 > + * StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0 > + * StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0 > + * StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0 > + * StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0 > + * StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1 > + * StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1 > + * StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2 > + * StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2 > + * StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0 > + * StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0 > + * StringUtils.indexOfDifference(new String[] {"i am a machine", "i > am a robot"}) = 7 > + * </pre> > + * > + * @param css array of CharSequences, entries may be null > + * @return the index where the strings begin to differ; -1 if they > are all > + * equal > + * @since 2.4 > + * @since 3.0 Changed signature from indexOfDifference(String...) to > + * indexOfDifference(CharSequence...) > + */ > + protected static int indexOfDifference(final CharSequence... css) { > + if (css == null || css.length <= 1) { > + return INDEX_NOT_FOUND; > + } > + boolean anyStringNull = false; > + boolean allStringsNull = true; > + final int arrayLen = css.length; > + int shortestStrLen = Integer.MAX_VALUE; > + int longestStrLen = 0; > + > + // find the min and max string lengths; this avoids checking to > make > + // sure we are not exceeding the length of the string each time > through > + // the bottom loop. > + for (int i = 0; i < arrayLen; i++) { > + if (css[i] == null) { > + anyStringNull = true; > + shortestStrLen = 0; > + } else { > + allStringsNull = false; > + shortestStrLen = Math.min(css[i].length(), > shortestStrLen); > + longestStrLen = Math.max(css[i].length(), longestStrLen); > + } > + } > + > + // handle lists containing all nulls or all empty strings > + if (allStringsNull || longestStrLen == 0 && !anyStringNull) { > + return INDEX_NOT_FOUND; > + } > + > + // handle lists containing some nulls or some empty strings > + if (shortestStrLen == 0) { > + return 0; > + } > + > + // find the position with the first difference across all strings > + int firstDiff = -1; > + for (int stringPos = 0; stringPos < shortestStrLen; stringPos++) { > + final char comparisonChar = css[0].charAt(stringPos); > + for (int arrayPos = 1; arrayPos < arrayLen; arrayPos++) { > + if (css[arrayPos].charAt(stringPos) != comparisonChar) { > + firstDiff = stringPos; > + break; > + } > + } > + if (firstDiff != -1) { > + break; > + } > + } > + > + if (firstDiff == -1 && shortestStrLen != longestStrLen) { > + // we compared all of the characters up to the length of the > + // shortest string and didn't find a match, but the string > lengths > + // vary, so return the length of the shortest string. > + return shortestStrLen; > + } > + return firstDiff; > + } > + > + /** > + * Gets a set of matching characters between two strings. > + * > + * <p> > + * Two characters from the first string and the second string are > + * considered matching if the character's respective positions are no > + * farther than the limit value. > + * </p> > + * > + * @param first The first string. > + * @param second The second string. > + * @param limit The maximum distance to consider. > + * @return A string contain the set of common characters. > + */ > + protected static String getSetOfMatchingCharacterWithin( > + final CharSequence first, final CharSequence second, final > int limit) { > + final StringBuilder common = new StringBuilder(); > + final StringBuilder copy = new StringBuilder(second); > + > + for (int i = 0; i < first.length(); i++) { > + final char ch = first.charAt(i); > + boolean found = false; > + > + // See if the character is within the limit positions away > from the > + // original position of that character. > + for (int j = Math.max(0, i - limit); !found > + && j < Math.min(i + limit, second.length()); j++) { > + if (copy.charAt(j) == ch) { > + found = true; > + common.append(ch); > + copy.setCharAt(j, '*'); > + } > + } > + } > + return common.toString(); > + } > + > +} > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/main/java/org/apache/commons/text/similarity/LevenshteinDistance.java > ---------------------------------------------------------------------- > diff --git > a/src/main/java/org/apache/commons/text/similarity/LevenshteinDistance.java > b/src/main/java/org/apache/commons/text/similarity/LevenshteinDistance.java > new file mode 100644 > index 0000000..1793f1e > --- /dev/null > +++ > b/src/main/java/org/apache/commons/text/similarity/LevenshteinDistance.java > @@ -0,0 +1,258 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +import java.util.Arrays; > + > +/** > + * <p> > + * A string metric for measuring the difference between two sequences. > + * </p> > + * > + * <p> > + * This code has been adapted from Apache Commons Lang 3.3. > + * </p> > + * > + * @since 1.0 > + */ > +public class LevenshteinDistance implements StringMetric<Integer> { > + > + /** > + * <p> > + * Find the Levenshtein distance between two Strings. > + * </p> > + * > + * <p> > + * This is the number of changes needed to change one String into > another, > + * where each change is a single character modification (deletion, > insertion > + * or substitution). > + * </p> > + * > + * <p> > + * The previous implementation of the Levenshtein distance algorithm > was > + * from <a > + * href="http://www.merriampark.com/ld.htm";> > http://www.merriampark.com > + * /ld.htm</a> > + * </p> > + * > + * <p> > + * Chas Emerick has written an implementation in Java, which avoids an > + * OutOfMemoryError which can occur when my Java implementation is > used with > + * very large strings.<br> > + * This implementation of the Levenshtein distance algorithm is from > <a > + * href="http://www.merriampark.com/ldjava.htm";> > http://www.merriampark.com/ > + * ldjava.htm</a> > + * </p> > + * > + * <pre> > + * StringUtils.getLevenshteinDistance(null, *) = > IllegalArgumentException > + * StringUtils.getLevenshteinDistance(*, null) = > IllegalArgumentException > + * StringUtils.getLevenshteinDistance("","") = 0 > + * StringUtils.getLevenshteinDistance("","a") = 1 > + * StringUtils.getLevenshteinDistance("aaapppp", "") = 7 > + * StringUtils.getLevenshteinDistance("frog", "fog") = 1 > + * StringUtils.getLevenshteinDistance("fly", "ant") = 3 > + * StringUtils.getLevenshteinDistance("elephant", "hippo") = 7 > + * StringUtils.getLevenshteinDistance("hippo", "elephant") = 7 > + * StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8 > + * StringUtils.getLevenshteinDistance("hello", "hallo") = 1 > + * </pre> > + * > + * @param left the first string, must not be null > + * @param right the second string, must not be null > + * @return result distance > + * @throws IllegalArgumentException if either String input {@code > null} > + */ > + @Override > + public Integer compare(CharSequence left, CharSequence right) { > + return compare(left, right, Integer.MAX_VALUE); > + } > + > + /** > + * <p> > + * Find the Levenshtein distance between two Strings if it's less > than or > + * equal to a given threshold. > + * </p> > + * > + * <p> > + * This is the number of changes needed to change one String into > another, > + * where each change is a single character modification (deletion, > insertion > + * or substitution). > + * </p> > + * > + * <p> > + * This implementation follows from Algorithms on Strings, Trees and > + * Sequences by Dan Gusfield and Chas Emerick's implementation of the > + * Levenshtein distance algorithm from <a > + * href="http://www.merriampark.com/ld.htm"; > + * >http://www.merriampark.com/ld.htm</a> > + * </p> > + * > + * <pre> > + * StringUtils.getLevenshteinDistance(null, *, *) = > IllegalArgumentException > + * StringUtils.getLevenshteinDistance(*, null, *) = > IllegalArgumentException > + * StringUtils.getLevenshteinDistance(*, *, -1) = > IllegalArgumentException > + * StringUtils.getLevenshteinDistance("","", 0) = 0 > + * StringUtils.getLevenshteinDistance("aaapppp", "", 8) = 7 > + * StringUtils.getLevenshteinDistance("aaapppp", "", 7) = 7 > + * StringUtils.getLevenshteinDistance("aaapppp", "", 6)) = -1 > + * StringUtils.getLevenshteinDistance("elephant", "hippo", 7) = 7 > + * StringUtils.getLevenshteinDistance("elephant", "hippo", 6) = -1 > + * StringUtils.getLevenshteinDistance("hippo", "elephant", 7) = 7 > + * StringUtils.getLevenshteinDistance("hippo", "elephant", 6) = -1 > + * </pre> > + * > + * @param left the first string, must not be null > + * @param right the second string, must not be null > + * @param threshold the target threshold, must not be negative > + * @return result distance > + * @throws IllegalArgumentException if either String input {@code > null} or > + * negative threshold > + */ > + public Integer compare(CharSequence left, CharSequence right, int > threshold) { > + if (left == null || right == null) { > + throw new IllegalArgumentException("Strings must not be > null"); > + } > + if (threshold < 0) { > + throw new IllegalArgumentException("Threshold must not be > negative"); > + } > + > + /* > + * This implementation only computes the distance if it's less > than or > + * equal to the threshold value, returning -1 if it's greater. The > + * advantage is performance: unbounded distance is O(nm), but a > bound of > + * k allows us to reduce it to O(km) time by only computing a > diagonal > + * stripe of width 2k + 1 of the cost table. It is also possible > to use > + * this to compute the unbounded Levenshtein distance by starting > the > + * threshold at 1 and doubling each time until the distance is > found; > + * this is O(dm), where d is the distance. > + * > + * One subtlety comes from needing to ignore entries on the > border of > + * our stripe eg. p[] = |#|#|#|* d[] = *|#|#|#| We must ignore > the entry > + * to the left of the leftmost member We must ignore the entry > above the > + * rightmost member > + * > + * Another subtlety comes from our stripe running off the matrix > if the > + * strings aren't of the same size. Since string s is always > swapped to > + * be the shorter of the two, the stripe will always run off to > the > + * upper right instead of the lower left of the matrix. > + * > + * As a concrete example, suppose s is of length 5, t is of > length 7, > + * and our threshold is 1. In this case we're going to walk a > stripe of > + * length 3. The matrix would look like so: > + * > + * 1 2 3 4 5 1 |#|#| | | | 2 |#|#|#| | | 3 | |#|#|#| | 4 | | > |#|#|#| 5 | > + * | | |#|#| 6 | | | | |#| 7 | | | | | | > + * > + * Note how the stripe leads off the table as there is no > possible way > + * to turn a string of length 5 into one of length 7 in edit > distance of > + * 1. > + * > + * Additionally, this implementation decreases memory usage by > using two > + * single-dimensional arrays and swapping them back and forth > instead of > + * allocating an entire n by m matrix. This requires a few minor > + * changes, such as immediately returning when it's detected that > the > + * stripe has run off the matrix and initially filling the arrays > with > + * large values so that entries we don't compute are ignored. > + * > + * See Algorithms on Strings, Trees and Sequences by Dan Gusfield > for > + * some discussion. > + */ > + > + int n = left.length(); // length of s > + int m = right.length(); // length of t > + > + // if one string is empty, the edit distance is necessarily the > length > + // of the other > + if (n == 0) { > + return m <= threshold ? m : -1; > + } else if (m == 0) { > + return n <= threshold ? n : -1; > + } > + > + if (n > m) { > + // swap the two strings to consume less memory > + final CharSequence tmp = left; > + left = right; > + right = tmp; > + n = m; > + m = right.length(); > + } > + > + int[] p = new int[n + 1]; // 'previous' cost array, horizontally > + int[] d = new int[n + 1]; // cost array, horizontally > + int[] _d; // placeholder to assist in swapping p and d > + > + // fill in starting table values > + final int boundary = Math.min(n, threshold) + 1; > + for (int i = 0; i < boundary; i++) { > + p[i] = i; > + } > + // these fills ensure that the value above the rightmost entry of > our > + // stripe will be ignored in following loop iterations > + Arrays.fill(p, boundary, p.length, Integer.MAX_VALUE); > + Arrays.fill(d, Integer.MAX_VALUE); > + > + // iterates through t > + for (int j = 1; j <= m; j++) { > + final char t_j = right.charAt(j - 1); // jth character of t > + d[0] = j; > + > + // compute stripe indices, constrain to array size > + final int min = Math.max(1, j - threshold); > + final int max = j > Integer.MAX_VALUE - threshold ? n : > Math.min( > + n, j + threshold); > + > + // the stripe may lead off of the table if s and t are of > different > + // sizes > + if (min > max) { > + return -1; > + } > + > + // ignore entry left of leftmost > + if (min > 1) { > + d[min - 1] = Integer.MAX_VALUE; > + } > + > + // iterates through [min, max] in s > + for (int i = min; i <= max; i++) { > + if (left.charAt(i - 1) == t_j) { > + // diagonally left and up > + d[i] = p[i - 1]; > + } else { > + // 1 + minimum of cell to the left, to the top, > diagonally > + // left and up > + d[i] = 1 + Math.min(Math.min(d[i - 1], p[i]), p[i - > 1]); > + } > + } > + > + // copy current distance counts to 'previous row' distance > counts > + _d = p; > + p = d; > + d = _d; > + } > + > + // if p[n] is greater than the threshold, there's no guarantee on > it > + // being the correct > + // distance > + if (p[n] <= threshold) { > + return p[n]; > + } > + return -1; > + } > + > +} > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/main/java/org/apache/commons/text/similarity/StringMetric.java > ---------------------------------------------------------------------- > diff --git > a/src/main/java/org/apache/commons/text/similarity/StringMetric.java > b/src/main/java/org/apache/commons/text/similarity/StringMetric.java > new file mode 100644 > index 0000000..6765bbd > --- /dev/null > +++ b/src/main/java/org/apache/commons/text/similarity/StringMetric.java > @@ -0,0 +1,45 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +/** > + * <p> > + * Marker interface for <a > + * href='http://en.wikipedia.org/wiki/String_metric'>String Metrics</a> > + * </p> > + * > + * <p> > + * A string metric measures the distance between two text strings. > + * </p> > + * > + * @param <R> return type of the edit distance > + * @since 1.0 > + */ > +public interface StringMetric<R> { > + > + /** > + * <p> > + * Compares two strings. > + * </p> > + * > + * @param left the first string > + * @param right the second string > + * @return result distance > + */ > + R compare(CharSequence left, CharSequence right); > + > +} > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/main/java/org/apache/commons/text/similarity/package-info.java > ---------------------------------------------------------------------- > diff --git > a/src/main/java/org/apache/commons/text/similarity/package-info.java > b/src/main/java/org/apache/commons/text/similarity/package-info.java > new file mode 100644 > index 0000000..8e9d478 > --- /dev/null > +++ b/src/main/java/org/apache/commons/text/similarity/package-info.java > @@ -0,0 +1,22 @@ > +/* > + * 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. > + */ > +/** > + * <p>Provides algorithms for string similarity.</p> > + * > + * @since 1.0 > + */ > +package org.apache.commons.text.similarity; > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/test/java/org/apache/commons/text/similarity/TestFuzzyDistance.java > ---------------------------------------------------------------------- > diff --git > a/src/test/java/org/apache/commons/text/similarity/TestFuzzyDistance.java > b/src/test/java/org/apache/commons/text/similarity/TestFuzzyDistance.java > new file mode 100644 > index 0000000..30b1dfc > --- /dev/null > +++ > b/src/test/java/org/apache/commons/text/similarity/TestFuzzyDistance.java > @@ -0,0 +1,75 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +import static org.junit.Assert.assertEquals; > + > +import java.util.Locale; > + > +import org.junit.BeforeClass; > +import org.junit.Test; > + > +/** > + * Unit tests for {@link org.apache.commons.text.FuzzyDistance}. > + */ > +public class TestFuzzyDistance { > + > + private static FuzzyDistance distance; > + > + @BeforeClass > + public static void setUp() { > + distance = new FuzzyDistance(); > + } > + > + @Test > + public void testGetFuzzyDistance() throws Exception { > + assertEquals(0, (int) distance.compare("", "", Locale.ENGLISH)); > + assertEquals(0, > + (int) distance.compare("Workshop", "b", Locale.ENGLISH)); > + assertEquals(1, > + (int) distance.compare("Room", "o", Locale.ENGLISH)); > + assertEquals(1, > + (int) distance.compare("Workshop", "w", Locale.ENGLISH)); > + assertEquals(2, > + (int) distance.compare("Workshop", "ws", Locale.ENGLISH)); > + assertEquals(4, > + (int) distance.compare("Workshop", "wo", Locale.ENGLISH)); > + assertEquals(3, (int) distance.compare( > + "Apache Software Foundation", "asf", Locale.ENGLISH)); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetFuzzyDistance_NullNullNull() throws Exception { > + distance.compare(null, null, null); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetFuzzyDistance_StringNullLoclae() throws Exception { > + distance.compare(" ", null, Locale.ENGLISH); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetFuzzyDistance_NullStringLocale() throws Exception { > + distance.compare(null, "clear", Locale.ENGLISH); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetFuzzyDistance_StringStringNull() throws Exception { > + distance.compare(" ", "clear", null); > + } > + > +} > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/test/java/org/apache/commons/text/similarity/TestJaroWrinklerDistance.java > ---------------------------------------------------------------------- > diff --git > a/src/test/java/org/apache/commons/text/similarity/TestJaroWrinklerDistance.java > b/src/test/java/org/apache/commons/text/similarity/TestJaroWrinklerDistance.java > new file mode 100644 > index 0000000..6477de0 > --- /dev/null > +++ > b/src/test/java/org/apache/commons/text/similarity/TestJaroWrinklerDistance.java > @@ -0,0 +1,62 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +import static org.junit.Assert.assertEquals; > + > +import org.junit.BeforeClass; > +import org.junit.Test; > + > +/** > + * Unit tests for {@link org.apache.commons.text.JaroWrinklerDistance}. > + */ > +public class TestJaroWrinklerDistance { > + > + private static JaroWrinklerDistance distance; > + > + @BeforeClass > + public static void setUp() { > + distance = new JaroWrinklerDistance(); > + } > + > + @Test > + public void testGetJaroWinklerDistance_StringString() { > + assertEquals(0.93d, (double) distance.compare("frog", "fog"), > 0.0d); > + assertEquals(0.0d, (double) distance.compare("fly", "ant"), 0.0d); > + assertEquals(0.44d, (double) distance.compare("elephant", > "hippo"), 0.0d); > + assertEquals(0.91d, (double) distance.compare("ABC Corporation", > "ABC Corp"), 0.0d); > + assertEquals(0.93d, (double) distance.compare("D N H Enterprises > Inc", "D & H Enterprises, Inc."), 0.0d); > + assertEquals(0.94d, (double) distance.compare("My Gym Children's > Fitness Center", "My Gym. Childrens Fitness"), 0.0d); > + assertEquals(0.9d, (double) distance.compare("PENNSYLVANIA", > "PENNCISYLVNIA"), 0.0d); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetJaroWinklerDistance_NullNull() throws Exception { > + distance.compare(null, null); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetJaroWinklerDistance_StringNull() throws Exception { > + distance.compare(" ", null); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetJaroWinklerDistance_NullString() throws Exception { > + distance.compare(null, "clear"); > + } > + > +} > > > http://git-wip-us.apache.org/repos/asf/commons-text/blob/c0e8c021/src/test/java/org/apache/commons/text/similarity/TestLevenshteinDistance.java > ---------------------------------------------------------------------- > diff --git > a/src/test/java/org/apache/commons/text/similarity/TestLevenshteinDistance.java > b/src/test/java/org/apache/commons/text/similarity/TestLevenshteinDistance.java > new file mode 100644 > index 0000000..7790b05 > --- /dev/null > +++ > b/src/test/java/org/apache/commons/text/similarity/TestLevenshteinDistance.java > @@ -0,0 +1,146 @@ > +/* > + * 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. > + */ > +package org.apache.commons.text.similarity; > + > +import static org.junit.Assert.assertEquals; > + > +import org.junit.BeforeClass; > +import org.junit.Test; > + > +/** > + * Unit tests for {@link org.apache.commons.text.LevenshteinDistance}. > + */ > +public class TestLevenshteinDistance { > + > + private static LevenshteinDistance distance; > + > + @BeforeClass > + public static void setUp() { > + distance = new LevenshteinDistance(); > + } > + > + @Test > + public void testGetLevenshteinDistance_StringString() { > + assertEquals(0, (int) distance.compare("", "")); > + assertEquals(1, (int) distance.compare("", "a")); > + assertEquals(7, (int) distance.compare("aaapppp", "")); > + assertEquals(1, (int) distance.compare("frog", "fog")); > + assertEquals(3, (int) distance.compare("fly", "ant")); > + assertEquals(7, (int) distance.compare("elephant", "hippo")); > + assertEquals(7, (int) distance.compare("hippo", "elephant")); > + assertEquals(8, (int) distance.compare("hippo", "zzzzzzzz")); > + assertEquals(8, (int) distance.compare("zzzzzzzz", "hippo")); > + assertEquals(1, (int) distance.compare("hello", "hallo")); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetLevenshteinDistance_NullString() throws Exception { > + distance.compare("a", null); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetLevenshteinDistance_StringNull() throws Exception { > + distance.compare(null, "a"); > + } > + > + @Test > + public void testGetLevenshteinDistance_StringStringInt() { > + // empty strings > + assertEquals(0, (int) distance.compare("", "", 0)); > + assertEquals(7, (int) distance.compare("aaapppp", "", 8)); > + assertEquals(7, (int) distance.compare("aaapppp", "", 7)); > + assertEquals(-1, (int) distance.compare("aaapppp", "", 6)); > + > + // unequal strings, zero threshold > + assertEquals(-1, (int) distance.compare("b", "a", 0)); > + assertEquals(-1, (int) distance.compare("a", "b", 0)); > + > + // equal strings > + assertEquals(0, (int) distance.compare("aa", "aa", 0)); > + assertEquals(0, (int) distance.compare("aa", "aa", 2)); > + > + // same length > + assertEquals(-1, (int) distance.compare("aaa", "bbb", 2)); > + assertEquals(3, (int) distance.compare("aaa", "bbb", 3)); > + > + // big stripe > + assertEquals(6, (int) distance.compare("aaaaaa", "b", 10)); > + > + // distance less than threshold > + assertEquals(7, (int) distance.compare("aaapppp", "b", 8)); > + assertEquals(3, (int) distance.compare("a", "bbb", 4)); > + > + // distance equal to threshold > + assertEquals(7, (int) distance.compare("aaapppp", "b", 7)); > + assertEquals(3, (int) distance.compare("a", "bbb", 3)); > + > + // distance greater than threshold > + assertEquals(-1, (int) distance.compare("a", "bbb", 2)); > + assertEquals(-1, (int) distance.compare("bbb", "a", 2)); > + assertEquals(-1, (int) distance.compare("aaapppp", "b", 6)); > + > + // stripe runs off array, strings not similar > + assertEquals(-1, (int) distance.compare("a", "bbb", 1)); > + assertEquals(-1, (int) distance.compare("bbb", "a", 1)); > + > + // stripe runs off array, strings are similar > + assertEquals(-1, (int) distance.compare("12345", "1234567", 1)); > + assertEquals(-1, (int) distance.compare("1234567", "12345", 1)); > + > + // old getLevenshteinDistance test cases > + assertEquals(1, (int) distance.compare("frog", "fog", 1)); > + assertEquals(3, (int) distance.compare("fly", "ant", 3)); > + assertEquals(7, (int) distance.compare("elephant", "hippo", 7)); > + assertEquals(-1, (int) distance.compare("elephant", "hippo", 6)); > + assertEquals(7, (int) distance.compare("hippo", "elephant", 7)); > + assertEquals(-1, (int) distance.compare("hippo", "elephant", 6)); > + assertEquals(8, (int) distance.compare("hippo", "zzzzzzzz", 8)); > + assertEquals(8, (int) distance.compare("zzzzzzzz", "hippo", 8)); > + assertEquals(1, (int) distance.compare("hello", "hallo", 1)); > + > + assertEquals(1, > + (int) distance.compare("frog", "fog", Integer.MAX_VALUE)); > + assertEquals(3, (int) distance.compare("fly", "ant", > Integer.MAX_VALUE)); > + assertEquals(7, > + (int) distance.compare("elephant", "hippo", > Integer.MAX_VALUE)); > + assertEquals(7, > + (int) distance.compare("hippo", "elephant", > Integer.MAX_VALUE)); > + assertEquals(8, > + (int) distance.compare("hippo", "zzzzzzzz", > Integer.MAX_VALUE)); > + assertEquals(8, > + (int) distance.compare("zzzzzzzz", "hippo", > Integer.MAX_VALUE)); > + assertEquals(1, > + (int) distance.compare("hello", "hallo", > Integer.MAX_VALUE)); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetLevenshteinDistance_NullStringInt() throws > Exception { > + distance.compare(null, "a", 0); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetLevenshteinDistance_StringNullInt() throws > Exception { > + distance.compare("a", null, 0); > + } > + > + @Test(expected = IllegalArgumentException.class) > + public void testGetLevenshteinDistance_StringStringNegativeInt() > + throws Exception { > + distance.compare("a", "a", -1); > + } > + > +} > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > > -- http://people.apache.org/~britter/ http://www.systemoutprintln.de/ http://twitter.com/BenediktRitter http://github.com/britter
