Java tutorial
/* * (c) 2005 David B. Bracewell * * 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 com.davidbracewell.string; import com.google.common.base.Predicate; import com.google.common.base.Predicates; import com.google.common.base.Strings; import javax.annotation.Nullable; /** * Commonly used predicates over strings. * * @author David B. Bracewell */ public enum StringPredicates implements Predicate<CharSequence> { /** * True if the input string is null */ IS_NULL { @Override public boolean apply(@Nullable CharSequence input) { return input == null; } }, /** * Determines if the string is null or empty, i.e. length of 0 */ IS_NULL_OR_EMPTY { @Override public boolean apply(@Nullable CharSequence input) { return Strings.isNullOrEmpty(input.toString()); } }, /** * True if the input string is null or blank (trimmed version is empty) */ IS_NULL_OR_BLANK { @Override public boolean apply(@Nullable CharSequence input) { return IS_NULL.apply(input) || StringUtils.trim(input.toString()).isEmpty(); } }, /** * True if the input string is in all lower case */ IS_LOWER_CASE { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (!Character.isLowerCase(input.charAt(i))) { return false; } } return true; } }, /** * True if the input string is in all upper case */ IS_UPPER_CASE { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (!Character.isUpperCase(input.charAt(i))) { return false; } } return true; } }, /** * True if the input string is all letter or digits */ IS_LETTER_OR_DIGIT { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { char c = input.charAt(i); if (!Character.isAlphabetic((int) c) && !Character.isDigit((int) c)) { return false; } } return true; } }, /** * True if the input string is all letters */ IS_LETTER { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { char c = input.charAt(i); if (!Character.isAlphabetic((int) c)) { return false; } } return true; } }, /** * True if the input string is all digits */ IS_DIGIT { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { char c = input.charAt(i); if (!Character.isDigit((int) c)) { return false; } } return true; } }, /** * True if the input string is all punctuation */ IS_PUNCTUATION { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { char c = input.charAt(i); if (!StringUtils.isPunctuation(c)) { return false; } } return true; } }, /** * True if the first character in the string is upper case */ HAS_INITIAL_CAPITAL_LETTER { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } return Character.isUpperCase(input.charAt(0)); } }, /** * True if any character in the string is upper case */ HAS_CAPITAL_LETTER { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (Character.isUpperCase(input.charAt(i))) { return true; } } return false; } }, /** * True if any character in the string is punctuation */ HAS_PUNCTUATION { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (StringUtils.isPunctuation(input.charAt(i))) { return true; } } return false; } }, /** * True if any character in the string is a digit */ HAS_DIGIT { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (Character.isDigit(input.charAt(i))) { return true; } } return false; } }, /** * True if any character in the string is a letter */ HAS_LETTER { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (Character.isLetter(input.charAt(i))) { return true; } } return false; } }, /** * True if any character in the string is a letter or digit */ HAS_LETTER_OR_DIGIT { @Override public boolean apply(@Nullable CharSequence input) { if (IS_NULL_OR_BLANK.apply(input)) { return false; } for (int i = 0; i < input.length(); i++) { if (Character.isLetter(input.charAt(i)) || Character.isDigit(input.charAt(i))) { return true; } } return false; } }; /** * Returns a method that performs an exact match on two charsequences * * @param toMatch the sequence to match * @return the predicate */ public static Predicate<CharSequence> MATCHES(String toMatch) { return MATCHES(toMatch, true); } /** * Returns a method that performs a match on two charsequences using {@link String#equals(Object)} or {@link * String#equalsIgnoreCase(String)} * * @param toMatch the sequence to match * @param caseSensitive True case sensitive match, False case insensitive * @return the predicate */ public static Predicate<CharSequence> MATCHES(String toMatch, boolean caseSensitive) { return new MatchPredicate(StringFunctions.NULL_TO_EMPTY.apply(toMatch), caseSensitive); } /** * Returns a method that checks if a text is contained an given string. * * @param text The text to check for * @return the predicate */ public static Predicate<CharSequence> CONTAINS(String text) { return CONTAINS(text, true); } /** * Returns a method that checks if a text is contained an given string. * * @param text The text to check for * @param caseSensitive True case sensitive match, False case insensitive * @return the predicate */ public static Predicate<CharSequence> CONTAINS(String text, boolean caseSensitive) { return new ContainsPredicate(caseSensitive, text); } /** * Creates a predicate that matches a given regular expression * * @param pattern the pattern to match * @return the predicate */ public static Predicate<CharSequence> REGEX_MATCH(String pattern) { return Predicates.containsPattern(pattern); } /** * Creates a predicate that matches the beginning of a string * * @param toMatch the sequence to match * @param caseSensitive True case sensitive match, False case insensitive * @return the predicate */ public static Predicate<CharSequence> STARTS_WITH(String toMatch, boolean caseSensitive) { return new StartsWithPredicate(StringFunctions.NULL_TO_EMPTY.apply(toMatch), caseSensitive); } /** * Creates a predicate that matches the ending of a string * * @param toMatch the sequence to match * @param caseSensitive True case sensitive match, False case insensitive * @return the predicate */ public static Predicate<CharSequence> ENDS_WITH(String toMatch, boolean caseSensitive) { return new EndsWithPredicate(StringFunctions.NULL_TO_EMPTY.apply(toMatch), caseSensitive); } private static class StartsWithPredicate implements Predicate<CharSequence> { private final boolean caseSensitive; private final String toMatch; private StartsWithPredicate(String toMatch, boolean caseSensitive) { this.toMatch = caseSensitive ? toMatch : toMatch.toLowerCase(); this.caseSensitive = caseSensitive; } @Override public boolean apply(@Nullable CharSequence input) { if (input == null) { return false; } else if (caseSensitive) { return input.toString().startsWith(toMatch); } return input.toString().toLowerCase().startsWith(toMatch); } } private static class EndsWithPredicate implements Predicate<CharSequence> { private final boolean caseSensitive; private final String toMatch; private EndsWithPredicate(String toMatch, boolean caseSensitive) { this.toMatch = caseSensitive ? toMatch : toMatch.toLowerCase(); this.caseSensitive = caseSensitive; } @Override public boolean apply(@Nullable CharSequence input) { if (input == null) { return false; } else if (caseSensitive) { return input.toString().endsWith(toMatch); } return input.toString().toLowerCase().endsWith(toMatch); } } private static class MatchPredicate implements Predicate<CharSequence> { private final boolean caseSensitive; private final String toMatch; private MatchPredicate(String toMatch, boolean caseSensitive) { this.toMatch = toMatch; this.caseSensitive = caseSensitive; } @Override public boolean apply(@Nullable CharSequence input) { if (input == null) { return false; } else if (caseSensitive) { return input.toString().equals(toMatch); } return input.toString().equalsIgnoreCase(toMatch); } } private static class ContainsPredicate implements Predicate<CharSequence> { private final boolean caseSensitive; private final String toMatch; private ContainsPredicate(boolean caseSensitive, String toMatch) { this.caseSensitive = caseSensitive; this.toMatch = caseSensitive ? toMatch : toMatch.toLowerCase(); } @Override public boolean apply(@Nullable CharSequence input) { if (input == null) { return false; } if (caseSensitive) { return input.toString().contains(toMatch); } return input.toString().toLowerCase().contains(toMatch); } } }//END OF StringPredicates