    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017    package org.apache.commons.lang;
    018
    019    import org.apache.commons.lang.math.NumberUtils;
    020
    021    /**
    022     * <p>Operations on boolean primitives and Boolean objects.</p>
    023     *
    024     * <p>This class tries to handle <code>null</code> input gracefully.
    025     * An exception will not be thrown for a <code>null</code> input.
    026     * Each method documents its behaviour in more detail.</p>
    027     *
    028     * @author Apache Software Foundation
    029     * @author Matthew Hawthorne
    030     * @author Gary Gregory
    031     * @since 2.0
    032     * @version $Id: BooleanUtils.java 905636 2010-02-02 14:03:32Z niallp $
    033     */
    034    public class BooleanUtils {
    035
    036        /**
    037         * <p><code>BooleanUtils</code> instances should NOT be constructed in standard programming.
    038         * Instead, the class should be used as <code>BooleanUtils.toBooleanObject(true);</code>.</p>
    039         *
    040         * <p>This constructor is public to permit tools that require a JavaBean instance
    041         * to operate.</p>
    042         */
    043        public BooleanUtils() {
    044          super();
    045        }
    046
    047        // Boolean utilities
    048        //--------------------------------------------------------------------------
    049        /**
    050         * <p>Negates the specified boolean.</p>
    051         *
    052         * <p>If <code>null</code> is passed in, <code>null</code> will be returned.</p>
    053         *
    054         * <pre>
    055         *   BooleanUtils.negate(Boolean.TRUE)  = Boolean.FALSE;
    056         *   BooleanUtils.negate(Boolean.FALSE) = Boolean.TRUE;
    057         *   BooleanUtils.negate(null)          = null;
    058         * </pre>
    059         *
    060         * @param bool  the Boolean to negate, may be null
    061         * @return the negated Boolean, or <code>null</code> if <code>null</code> input
    062         */
    063        public static Boolean negate(Boolean bool) {
    064            if (bool == null) {
    065                return null;
    066            }
    067            return (bool.booleanValue() ? Boolean.FALSE : Boolean.TRUE);
    068        }
    069
    070        // boolean Boolean methods
    071        //-----------------------------------------------------------------------
    072        /**
    073         * <p>Checks if a <code>Boolean</code> value is <code>true</code>,
    074         * handling <code>null</code> by returning <code>false</code>.</p>
    075         *
    076         * <pre>
    077         *   BooleanUtils.isTrue(Boolean.TRUE)  = true
    078         *   BooleanUtils.isTrue(Boolean.FALSE) = false
    079         *   BooleanUtils.isTrue(null)          = false
    080         * </pre>
    081         *
    082         * @param bool  the boolean to check, null returns <code>false</code>
    083         * @return <code>true</code> only if the input is non-null and true
    084         * @since 2.1
    085         */
    086        public static boolean isTrue(Boolean bool) {
    087            if (bool == null) {
    088                return false;
    089            }
    090            return bool.booleanValue() ? true : false;
    091        }
    092
    093        /**
    094         * <p>Checks if a <code>Boolean</code> value is <i>not</i> <code>true</code>,
    095         * handling <code>null</code> by returning <code>true</code>.</p>
    096         *
    097         * <pre>
    098         *   BooleanUtils.isNotTrue(Boolean.TRUE)  = false
    099         *   BooleanUtils.isNotTrue(Boolean.FALSE) = true
    100         *   BooleanUtils.isNotTrue(null)          = true
    101         * </pre>
    102         *
    103         * @param bool  the boolean to check, null returns <code>true</code>
    104         * @return <code>true</code> if the input is null or false
    105         * @since 2.3
    106         */
    107        public static boolean isNotTrue(Boolean bool) {
    108            return !isTrue(bool);
    109        }
    110
    111        /**
    112         * <p>Checks if a <code>Boolean</code> value is <code>false</code>,
    113         * handling <code>null</code> by returning <code>false</code>.</p>
    114         *
    115         * <pre>
    116         *   BooleanUtils.isFalse(Boolean.TRUE)  = false
    117         *   BooleanUtils.isFalse(Boolean.FALSE) = true
    118         *   BooleanUtils.isFalse(null)          = false
    119         * </pre>
    120         *
    121         * @param bool  the boolean to check, null returns <code>false</code>
    122         * @return <code>true</code> only if the input is non-null and false
    123         * @since 2.1
    124         */
    125        public static boolean isFalse(Boolean bool) {
    126            if (bool == null) {
    127                return false;
    128            }
    129            return bool.booleanValue() ? false : true;
    130        }
    131
    132        /**
    133         * <p>Checks if a <code>Boolean</code> value is <i>not</i> <code>false</code>,
    134         * handling <code>null</code> by returning <code>true</code>.</p>
    135         *
    136         * <pre>
    137         *   BooleanUtils.isNotFalse(Boolean.TRUE)  = true
    138         *   BooleanUtils.isNotFalse(Boolean.FALSE) = false
    139         *   BooleanUtils.isNotFalse(null)          = true
    140         * </pre>
    141         *
    142         * @param bool  the boolean to check, null returns <code>true</code>
    143         * @return <code>true</code> if the input is null or true
    144         * @since 2.3
    145         */
    146        public static boolean isNotFalse(Boolean bool) {
    147            return !isFalse(bool);
    148        }
    149
    150        //-----------------------------------------------------------------------
    151        /**
    152         * <p>Boolean factory that avoids creating new Boolean objecs all the time.</p>
    153         *
    154         * <p>This method was added to JDK1.4 but is available here for earlier JDKs.</p>
    155         *
    156         * <pre>
    157         *   BooleanUtils.toBooleanObject(false) = Boolean.FALSE
    158         *   BooleanUtils.toBooleanObject(true)  = Boolean.TRUE
    159         * </pre>
    160         *
    161         * @param bool  the boolean to convert
    162         * @return Boolean.TRUE or Boolean.FALSE as appropriate
    163         */
    164        public static Boolean toBooleanObject(boolean bool) {
    165            return bool ? Boolean.TRUE : Boolean.FALSE;
    166        }
    167
    168        /**
    169         * <p>Converts a Boolean to a boolean handling <code>null</code>
    170         * by returning <code>false</code>.</p>
    171         *
    172         * <pre>
    173         *   BooleanUtils.toBoolean(Boolean.TRUE)  = true
    174         *   BooleanUtils.toBoolean(Boolean.FALSE) = false
    175         *   BooleanUtils.toBoolean(null)          = false
    176         * </pre>
    177         *
    178         * @param bool  the boolean to convert
    179         * @return <code>true</code> or <code>false</code>,
    180         *  <code>null</code> returns <code>false</code>
    181         */
    182        public static boolean toBoolean(Boolean bool) {
    183            if (bool == null) {
    184                return false;
    185            }
    186            return bool.booleanValue() ? true : false;
    187        }
    188
    189        /**
    190         * <p>Converts a Boolean to a boolean handling <code>null</code>.</p>
    191         *
    192         * <pre>
    193         *   BooleanUtils.toBooleanDefaultIfNull(Boolean.TRUE, false) = true
    194         *   BooleanUtils.toBooleanDefaultIfNull(Boolean.FALSE, true) = false
    195         *   BooleanUtils.toBooleanDefaultIfNull(null, true)          = true
    196         * </pre>
    197         *
    198         * @param bool  the boolean to convert
    199         * @param valueIfNull  the boolean value to return if <code>null</code>
    200         * @return <code>true</code> or <code>false</code>
    201         */
    202        public static boolean toBooleanDefaultIfNull(Boolean bool, boolean valueIfNull) {
    203            if (bool == null) {
    204                return valueIfNull;
    205            }
    206            return bool.booleanValue() ? true : false;
    207        }
    208
    209        // Integer to Boolean methods
    210        //-----------------------------------------------------------------------
    211        /**
    212         * <p>Converts an int to a boolean using the convention that <code>zero</code>
    213         * is <code>false</code>.</p>
    214         *
    215         * <pre>
    216         *   BooleanUtils.toBoolean(0) = false
    217         *   BooleanUtils.toBoolean(1) = true
    218         *   BooleanUtils.toBoolean(2) = true
    219         * </pre>
    220         *
    221         * @param value  the int to convert
    222         * @return <code>true</code> if non-zero, <code>false</code>
    223         *  if zero
    224         */
    225        public static boolean toBoolean(int value) {
    226            return value == 0 ? false : true;
    227        }
    228
    229        /**
    230         * <p>Converts an int to a Boolean using the convention that <code>zero</code>
    231         * is <code>false</code>.</p>
    232         *
    233         * <pre>
    234         *   BooleanUtils.toBoolean(0) = Boolean.FALSE
    235         *   BooleanUtils.toBoolean(1) = Boolean.TRUE
    236         *   BooleanUtils.toBoolean(2) = Boolean.TRUE
    237         * </pre>
    238         *
    239         * @param value  the int to convert
    240         * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero,
    241         *  <code>null</code> if <code>null</code>
    242         */
    243        public static Boolean toBooleanObject(int value) {
    244            return value == 0 ? Boolean.FALSE : Boolean.TRUE;
    245        }
    246
    247        /**
    248         * <p>Converts an Integer to a Boolean using the convention that <code>zero</code>
    249         * is <code>false</code>.</p>
    250         *
    251         * <p><code>null</code> will be converted to <code>null</code>.</p>
    252         *
    253         * <pre>
    254         *   BooleanUtils.toBoolean(new Integer(0))    = Boolean.FALSE
    255         *   BooleanUtils.toBoolean(new Integer(1))    = Boolean.TRUE
    256         *   BooleanUtils.toBoolean(new Integer(null)) = null
    257         * </pre>
    258         *
    259         * @param value  the Integer to convert
    260         * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero,
    261         *  <code>null</code> if <code>null</code> input
    262         */
    263        public static Boolean toBooleanObject(Integer value) {
    264            if (value == null) {
    265                return null;
    266            }
    267            return value.intValue() == 0 ? Boolean.FALSE : Boolean.TRUE;
    268        }
    269
    270        /**
    271         * <p>Converts an int to a boolean specifying the conversion values.</p>
    272         *
    273         * <pre>
    274         *   BooleanUtils.toBoolean(0, 1, 0) = false
    275         *   BooleanUtils.toBoolean(1, 1, 0) = true
    276         *   BooleanUtils.toBoolean(2, 1, 2) = false
    277         *   BooleanUtils.toBoolean(2, 2, 0) = true
    278         * </pre>
    279         *
    280         * @param value  the Integer to convert
    281         * @param trueValue  the value to match for <code>true</code>
    282         * @param falseValue  the value to match for <code>false</code>
    283         * @return <code>true</code> or <code>false</code>
    284         * @throws IllegalArgumentException if no match
    285         */
    286        public static boolean toBoolean(int value, int trueValue, int falseValue) {
    287            if (value == trueValue) {
    288                return true;
    289            } else if (value == falseValue) {
    290                return false;
    291            }
    292            // no match
    293            throw new IllegalArgumentException("The Integer did not match either specified value");
    294        }
    295
    296        /**
    297         * <p>Converts an Integer to a boolean specifying the conversion values.</p>
    298         *
    299         * <pre>
    300         *   BooleanUtils.toBoolean(new Integer(0), new Integer(1), new Integer(0)) = false
    301         *   BooleanUtils.toBoolean(new Integer(1), new Integer(1), new Integer(0)) = true
    302         *   BooleanUtils.toBoolean(new Integer(2), new Integer(1), new Integer(2)) = false
    303         *   BooleanUtils.toBoolean(new Integer(2), new Integer(2), new Integer(0)) = true
    304         *   BooleanUtils.toBoolean(null, null, new Integer(0))                     = true
    305         * </pre>
    306         *
    307         * @param value  the Integer to convert
    308         * @param trueValue  the value to match for <code>true</code>,
    309         *  may be <code>null</code>
    310         * @param falseValue  the value to match for <code>false</code>,
    311         *  may be <code>null</code>
    312         * @return <code>true</code> or <code>false</code>
    313         * @throws IllegalArgumentException if no match
    314         */
    315        public static boolean toBoolean(Integer value, Integer trueValue, Integer falseValue) {
    316            if (value == null) {
    317                if (trueValue == null) {
    318                    return true;
    319                } else if (falseValue == null) {
    320                    return false;
    321                }
    322            } else if (value.equals(trueValue)) {
    323                return true;
    324            } else if (value.equals(falseValue)) {
    325                return false;
    326            }
    327            // no match
    328            throw new IllegalArgumentException("The Integer did not match either specified value");
    329        }
    330
    331        /**
    332         * <p>Converts an int to a Boolean specifying the conversion values.</p>
    333         *
    334         * <pre>
    335         *   BooleanUtils.toBooleanObject(0, 0, 2, 3) = Boolean.TRUE
    336         *   BooleanUtils.toBooleanObject(2, 1, 2, 3) = Boolean.FALSE
    337         *   BooleanUtils.toBooleanObject(3, 1, 2, 3) = null
    338         * </pre>
    339         *
    340         * @param value  the Integer to convert
    341         * @param trueValue  the value to match for <code>true</code>
    342         * @param falseValue  the value to match for <code>false</code>
    343         * @param nullValue  the value to to match for <code>null</code>
    344         * @return Boolean.TRUE, Boolean.FALSE, or <code>null</code>
    345         * @throws IllegalArgumentException if no match
    346         */
    347        public static Boolean toBooleanObject(int value, int trueValue, int falseValue, int nullValue) {
    348            if (value == trueValue) {
    349                return Boolean.TRUE;
    350            } else if (value == falseValue) {
    351                return Boolean.FALSE;
    352            } else if (value == nullValue) {
    353                return null;
    354            }
    355            // no match
    356            throw new IllegalArgumentException("The Integer did not match any specified value");
    357        }
    358
    359        /**
    360         * <p>Converts an Integer to a Boolean specifying the conversion values.</p>
    361         *
    362         * <pre>
    363         *   BooleanUtils.toBooleanObject(new Integer(0), new Integer(0), new Integer(2), new Integer(3)) = Boolean.TRUE
    364         *   BooleanUtils.toBooleanObject(new Integer(2), new Integer(1), new Integer(2), new Integer(3)) = Boolean.FALSE
    365         *   BooleanUtils.toBooleanObject(new Integer(3), new Integer(1), new Integer(2), new Integer(3)) = null
    366         * </pre>
    367         *
    368         * @param value  the Integer to convert
    369         * @param trueValue  the value to match for <code>true</code>,
    370         *  may be <code>null</code>
    371         * @param falseValue  the value to match for <code>false</code>,
    372         *  may be <code>null</code>
    373         * @param nullValue  the value to to match for <code>null</code>,
    374         *  may be <code>null</code>
    375         * @return Boolean.TRUE, Boolean.FALSE, or <code>null</code>
    376         * @throws IllegalArgumentException if no match
    377         */
    378        public static Boolean toBooleanObject(Integer value, Integer trueValue, Integer falseValue, Integer nullValue) {
    379            if (value == null) {
    380                if (trueValue == null) {
    381                    return Boolean.TRUE;
    382                } else if (falseValue == null) {
    383                    return Boolean.FALSE;
    384                } else if (nullValue == null) {
    385                    return null;
    386                }
    387            } else if (value.equals(trueValue)) {
    388                return Boolean.TRUE;
    389            } else if (value.equals(falseValue)) {
    390                return Boolean.FALSE;
    391            } else if (value.equals(nullValue)) {
    392                return null;
    393            }
    394            // no match
    395            throw new IllegalArgumentException("The Integer did not match any specified value");
    396        }
    397
    398        // Boolean to Integer methods
    399        //-----------------------------------------------------------------------
    400        /**
    401         * <p>Converts a boolean to an int using the convention that
    402         * <code>zero</code> is <code>false</code>.</p>
    403         *
    404         * <pre>
    405         *   BooleanUtils.toInteger(true)  = 1
    406         *   BooleanUtils.toInteger(false) = 0
    407         * </pre>
    408         *
    409         * @param bool  the boolean to convert
    410         * @return one if <code>true</code>, zero if <code>false</code>
    411         */
    412        public static int toInteger(boolean bool) {
    413            return bool ? 1 : 0;
    414        }
    415
    416        /**
    417         * <p>Converts a boolean to an Integer using the convention that
    418         * <code>zero</code> is <code>false</code>.</p>
    419         *
    420         * <pre>
    421         *   BooleanUtils.toIntegerObject(true)  = new Integer(1)
    422         *   BooleanUtils.toIntegerObject(false) = new Integer(0)
    423         * </pre>
    424         *
    425         * @param bool  the boolean to convert
    426         * @return one if <code>true</code>, zero if <code>false</code>
    427         */
    428        public static Integer toIntegerObject(boolean bool) {
    429            return bool ? NumberUtils.INTEGER_ONE : NumberUtils.INTEGER_ZERO;
    430        }
    431
    432        /**
    433         * <p>Converts a Boolean to a Integer using the convention that
    434         * <code>zero</code> is <code>false</code>.</p>
    435         *
    436         * <p><code>null</code> will be converted to <code>null</code>.</p>
    437         *
    438         * <pre>
    439         *   BooleanUtils.toIntegerObject(Boolean.TRUE)  = new Integer(1)
    440         *   BooleanUtils.toIntegerObject(Boolean.FALSE) = new Integer(0)
    441         * </pre>
    442         *
    443         * @param bool  the Boolean to convert
    444         * @return one if Boolean.TRUE, zero if Boolean.FALSE, <code>null</code> if <code>null</code>
    445         */
    446        public static Integer toIntegerObject(Boolean bool) {
    447            if (bool == null) {
    448                return null;
    449            }
    450            return bool.booleanValue() ? NumberUtils.INTEGER_ONE : NumberUtils.INTEGER_ZERO;
    451        }
    452
    453        /**
    454         * <p>Converts a boolean to an int specifying the conversion values.</p>
    455         *
    456         * <pre>
    457         *   BooleanUtils.toInteger(true, 1, 0)  = 1
    458         *   BooleanUtils.toInteger(false, 1, 0) = 0
    459         * </pre>
    460         *
    461         * @param bool  the to convert
    462         * @param trueValue  the value to return if <code>true</code>
    463         * @param falseValue  the value to return if <code>false</code>
    464         * @return the appropriate value
    465         */
    466        public static int toInteger(boolean bool, int trueValue, int falseValue) {
    467            return bool ? trueValue : falseValue;
    468        }
    469
    470        /**
    471         * <p>Converts a Boolean to an int specifying the conversion values.</p>
    472         *
    473         * <pre>
    474         *   BooleanUtils.toInteger(Boolean.TRUE, 1, 0, 2)  = 1
    475         *   BooleanUtils.toInteger(Boolean.FALSE, 1, 0, 2) = 0
    476         *   BooleanUtils.toInteger(null, 1, 0, 2)          = 2
    477         * </pre>
    478         *
    479         * @param bool  the Boolean to convert
    480         * @param trueValue  the value to return if <code>true</code>
    481         * @param falseValue  the value to return if <code>false</code>
    482         * @param nullValue  the value to return if <code>null</code>
    483         * @return the appropriate value
    484         */
    485        public static int toInteger(Boolean bool, int trueValue, int falseValue, int nullValue) {
    486            if (bool == null) {
    487                return nullValue;
    488            }
    489            return bool.booleanValue() ? trueValue : falseValue;
    490        }
    491
    492        /**
    493         * <p>Converts a boolean to an Integer specifying the conversion values.</p>
    494         *
    495         * <pre>
    496         *   BooleanUtils.toIntegerObject(true, new Integer(1), new Integer(0))  = new Integer(1)
    497         *   BooleanUtils.toIntegerObject(false, new Integer(1), new Integer(0)) = new Integer(0)
    498         * </pre>
    499         *
    500         * @param bool  the to convert
    501         * @param trueValue  the value to return if <code>true</code>,
    502         *  may be <code>null</code>
    503         * @param falseValue  the value to return if <code>false</code>,
    504         *  may be <code>null</code>
    505         * @return the appropriate value
    506         */
    507        public static Integer toIntegerObject(boolean bool, Integer trueValue, Integer falseValue) {
    508            return bool ? trueValue : falseValue;
    509        }
    510
    511        /**
    512         * <p>Converts a Boolean to an Integer specifying the conversion values.</p>
    513         *
    514         * <pre>
    515         *   BooleanUtils.toIntegerObject(Boolean.TRUE, new Integer(1), new Integer(0), new Integer(2))  = new Integer(1)
    516         *   BooleanUtils.toIntegerObject(Boolean.FALSE, new Integer(1), new Integer(0), new Integer(2)) = new Integer(0)
    517         *   BooleanUtils.toIntegerObject(null, new Integer(1), new Integer(0), new Integer(2))          = new Integer(2)
    518         * </pre>
    519         *
    520         * @param bool  the Boolean to convert
    521         * @param trueValue  the value to return if <code>true</code>,
    522         *  may be <code>null</code>
    523         * @param falseValue  the value to return if <code>false</code>,
    524         *  may be <code>null</code>
    525         * @param nullValue  the value to return if <code>null</code>,
    526         *  may be <code>null</code>
    527         * @return the appropriate value
    528         */
    529        public static Integer toIntegerObject(Boolean bool, Integer trueValue, Integer falseValue, Integer nullValue) {
    530            if (bool == null) {
    531                return nullValue;
    532            }
    533            return bool.booleanValue() ? trueValue : falseValue;
    534        }
    535
    536        // String to Boolean methods
    537        //-----------------------------------------------------------------------
    538        /**
    539         * <p>Converts a String to a Boolean.</p>
    540         *
    541         * <p><code>'true'</code>, <code>'on'</code> or <code>'yes'</code>
    542         * (case insensitive) will return <code>true</code>.
    543         * <code>'false'</code>, <code>'off'</code> or <code>'no'</code>
    544         * (case insensitive) will return <code>false</code>.
    545         * Otherwise, <code>null</code> is returned.</p>
    546         *
    547         * <pre>
    548         *   BooleanUtils.toBooleanObject(null)    = null
    549         *   BooleanUtils.toBooleanObject("true")  = Boolean.TRUE
    550         *   BooleanUtils.toBooleanObject("false") = Boolean.FALSE
    551         *   BooleanUtils.toBooleanObject("on")    = Boolean.TRUE
    552         *   BooleanUtils.toBooleanObject("ON")    = Boolean.TRUE
    553         *   BooleanUtils.toBooleanObject("off")   = Boolean.FALSE
    554         *   BooleanUtils.toBooleanObject("oFf")   = Boolean.FALSE
    555         *   BooleanUtils.toBooleanObject("blue")  = null
    556         * </pre>
    557         *
    558         * @param str  the String to check
    559         * @return the Boolean value of the string,
    560         *  <code>null</code> if no match or <code>null</code> input
    561         */
    562        public static Boolean toBooleanObject(String str) {
    563            if ("true".equalsIgnoreCase(str)) {
    564                return Boolean.TRUE;
    565            } else if ("false".equalsIgnoreCase(str)) {
    566                return Boolean.FALSE;
    567            } else if ("on".equalsIgnoreCase(str)) {
    568                return Boolean.TRUE;
    569            } else if ("off".equalsIgnoreCase(str)) {
    570                return Boolean.FALSE;
    571            } else if ("yes".equalsIgnoreCase(str)) {
    572                return Boolean.TRUE;
    573            } else if ("no".equalsIgnoreCase(str)) {
    574                return Boolean.FALSE;
    575            }
    576            // no match
    577            return null;
    578        }
    579
    580        /**
    581         * <p>Converts a String to a Boolean throwing an exception if no match.</p>
    582         *
    583         * <pre>
    584         *   BooleanUtils.toBooleanObject("true", "true", "false", "null")  = Boolean.TRUE
    585         *   BooleanUtils.toBooleanObject("false", "true", "false", "null") = Boolean.FALSE
    586         *   BooleanUtils.toBooleanObject("null", "true", "false", "null")  = null
    587         * </pre>
    588         *
    589         * @param str  the String to check
    590         * @param trueString  the String to match for <code>true</code>
    591         *  (case sensitive), may be <code>null</code>
    592         * @param falseString  the String to match for <code>false</code>
    593         *  (case sensitive), may be <code>null</code>
    594         * @param nullString  the String to match for <code>null</code>
    595         *  (case sensitive), may be <code>null</code>
    596         * @return the Boolean value of the string,
    597         *  <code>null</code> if either the String matches <code>nullString</code>
    598         *  or if <code>null</code> input and <code>nullString</code> is
    599         *  <code>null</code>
    600         * @throws IllegalArgumentException if the String doesn't match
    601         */
    602        public static Boolean toBooleanObject(String str, String trueString, String falseString, String nullString) {
    603            if (str == null) {
    604                if (trueString == null) {
    605                    return Boolean.TRUE;
    606                } else if (falseString == null) {
    607                    return Boolean.FALSE;
    608                } else if (nullString == null) {
    609                    return null;
    610                }
    611            } else if (str.equals(trueString)) {
    612                return Boolean.TRUE;
    613            } else if (str.equals(falseString)) {
    614                return Boolean.FALSE;
    615            } else if (str.equals(nullString)) {
    616                return null;
    617            }
    618            // no match
    619            throw new IllegalArgumentException("The String did not match any specified value");
    620        }
    621
    622        // String to boolean methods
    623        //-----------------------------------------------------------------------
    624        /**
    625         * <p>Converts a String to a boolean (optimised for performance).</p>
    626         *
    627         * <p><code>'true'</code>, <code>'on'</code> or <code>'yes'</code>
    628         * (case insensitive) will return <code>true</code>. Otherwise,
    629         * <code>false</code> is returned.</p>
    630         *
    631         * <p>This method performs 4 times faster (JDK1.4) than
    632         * <code>Boolean.valueOf(String)</code>. However, this method accepts
    633         * 'on' and 'yes' as true values.
    634         *
    635         * <pre>
    636         *   BooleanUtils.toBoolean(null)    = false
    637         *   BooleanUtils.toBoolean("true")  = true
    638         *   BooleanUtils.toBoolean("TRUE")  = true
    639         *   BooleanUtils.toBoolean("tRUe")  = true
    640         *   BooleanUtils.toBoolean("on")    = true
    641         *   BooleanUtils.toBoolean("yes")   = true
    642         *   BooleanUtils.toBoolean("false") = false
    643         *   BooleanUtils.toBoolean("x gti") = false
    644         * </pre>
    645         *
    646         * @param str  the String to check
    647         * @return the boolean value of the string, <code>false</code> if no match
    648         */
    649        public static boolean toBoolean(String str) {
    650            // Previously used equalsIgnoreCase, which was fast for interned 'true'.
    651            // Non interned 'true' matched 15 times slower.
    652            //
    653            // Optimisation provides same performance as before for interned 'true'.
    654            // Similar performance for null, 'false', and other strings not length 2/3/4.
    655            // 'true'/'TRUE' match 4 times slower, 'tRUE'/'True' 7 times slower.
    656            if (str == "true") {
    657                return true;
    658            }
    659            if (str == null) {
    660                return false;
    661            }
    662            switch (str.length()) {
    663                case 2: {
    664                    char ch0 = str.charAt(0);
    665                    char ch1 = str.charAt(1);
    666                    return
    667                        (ch0 == 'o' || ch0 == 'O') &&
    668                        (ch1 == 'n' || ch1 == 'N');
    669                }
    670                case 3: {
    671                    char ch = str.charAt(0);
    672                    if (ch == 'y') {
    673                        return
    674                            (str.charAt(1) == 'e' || str.charAt(1) == 'E') &&
    675                            (str.charAt(2) == 's' || str.charAt(2) == 'S');
    676                    }
    677                    if (ch == 'Y') {
    678                        return
    679                            (str.charAt(1) == 'E' || str.charAt(1) == 'e') &&
    680                            (str.charAt(2) == 'S' || str.charAt(2) == 's');
    681                    }
    682                    return false;
    683                }
    684                case 4: {
    685                    char ch = str.charAt(0);
    686                    if (ch == 't') {
    687                        return
    688                            (str.charAt(1) == 'r' || str.charAt(1) == 'R') &&
    689                            (str.charAt(2) == 'u' || str.charAt(2) == 'U') &&
    690                            (str.charAt(3) == 'e' || str.charAt(3) == 'E');
    691                    }
    692                    if (ch == 'T') {
    693                        return
    694                            (str.charAt(1) == 'R' || str.charAt(1) == 'r') &&
    695                            (str.charAt(2) == 'U' || str.charAt(2) == 'u') &&
    696                            (str.charAt(3) == 'E' || str.charAt(3) == 'e');
    697                    }
    698                }
    699            }
    700            return false;
    701        }
    702
    703        /**
    704         * <p>Converts a String to a Boolean throwing an exception if no match found.</p>
    705         *
    706         * <p>null is returned if there is no match.</p>
    707         *
    708         * <pre>
    709         *   BooleanUtils.toBoolean("true", "true", "false")  = true
    710         *   BooleanUtils.toBoolean("false", "true", "false") = false
    711         * </pre>
    712         *
    713         * @param str  the String to check
    714         * @param trueString  the String to match for <code>true</code>
    715         *  (case sensitive), may be <code>null</code>
    716         * @param falseString  the String to match for <code>false</code>
    717         *  (case sensitive), may be <code>null</code>
    718         * @return the boolean value of the string
    719         * @throws IllegalArgumentException if the String doesn't match
    720         */
    721        public static boolean toBoolean(String str, String trueString, String falseString) {
    722            if (str == null) {
    723                if (trueString == null) {
    724                    return true;
    725                } else if (falseString == null) {
    726                    return false;
    727                }
    728            } else if (str.equals(trueString)) {
    729                return true;
    730            } else if (str.equals(falseString)) {
    731                return false;
    732            }
    733            // no match
    734            throw new IllegalArgumentException("The String did not match either specified value");
    735        }
    736
    737        // Boolean to String methods
    738        //-----------------------------------------------------------------------
    739        /**
    740         * <p>Converts a Boolean to a String returning <code>'true'</code>,
    741         * <code>'false'</code>, or <code>null</code>.</p>
    742         *
    743         * <pre>
    744         *   BooleanUtils.toStringTrueFalse(Boolean.TRUE)  = "true"
    745         *   BooleanUtils.toStringTrueFalse(Boolean.FALSE) = "false"
    746         *   BooleanUtils.toStringTrueFalse(null)          = null;
    747         * </pre>
    748         *
    749         * @param bool  the Boolean to check
    750         * @return <code>'true'</code>, <code>'false'</code>,
    751         *  or <code>null</code>
    752         */
    753        public static String toStringTrueFalse(Boolean bool) {
    754            return toString(bool, "true", "false", null);
    755        }
    756
    757        /**
    758         * <p>Converts a Boolean to a String returning <code>'on'</code>,
    759         * <code>'off'</code>, or <code>null</code>.</p>
    760         *
    761         * <pre>
    762         *   BooleanUtils.toStringOnOff(Boolean.TRUE)  = "on"
    763         *   BooleanUtils.toStringOnOff(Boolean.FALSE) = "off"
    764         *   BooleanUtils.toStringOnOff(null)          = null;
    765         * </pre>
    766         *
    767         * @param bool  the Boolean to check
    768         * @return <code>'on'</code>, <code>'off'</code>,
    769         *  or <code>null</code>
    770         */
    771        public static String toStringOnOff(Boolean bool) {
    772            return toString(bool, "on", "off", null);
    773        }
    774
    775        /**
    776         * <p>Converts a Boolean to a String returning <code>'yes'</code>,
    777         * <code>'no'</code>, or <code>null</code>.</p>
    778         *
    779         * <pre>
    780         *   BooleanUtils.toStringYesNo(Boolean.TRUE)  = "yes"
    781         *   BooleanUtils.toStringYesNo(Boolean.FALSE) = "no"
    782         *   BooleanUtils.toStringYesNo(null)          = null;
    783         * </pre>
    784         *
    785         * @param bool  the Boolean to check
    786         * @return <code>'yes'</code>, <code>'no'</code>,
    787         *  or <code>null</code>
    788         */
    789        public static String toStringYesNo(Boolean bool) {
    790            return toString(bool, "yes", "no", null);
    791        }
    792
    793        /**
    794         * <p>Converts a Boolean to a String returning one of the input Strings.</p>
    795         *
    796         * <pre>
    797         *   BooleanUtils.toString(Boolean.TRUE, "true", "false", null)   = "true"
    798         *   BooleanUtils.toString(Boolean.FALSE, "true", "false", null)  = "false"
    799         *   BooleanUtils.toString(null, "true", "false", null)           = null;
    800         * </pre>
    801         *
    802         * @param bool  the Boolean to check
    803         * @param trueString  the String to return if <code>true</code>,
    804         *  may be <code>null</code>
    805         * @param falseString  the String to return if <code>false</code>,
    806         *  may be <code>null</code>
    807         * @param nullString  the String to return if <code>null</code>,
    808         *  may be <code>null</code>
    809         * @return one of the three input Strings
    810         */
    811        public static String toString(Boolean bool, String trueString, String falseString, String nullString) {
    812            if (bool == null) {
    813                return nullString;
    814            }
    815            return bool.booleanValue() ? trueString : falseString;
    816        }
    817
    818        // boolean to String methods
    819        //-----------------------------------------------------------------------
    820        /**
    821         * <p>Converts a boolean to a String returning <code>'true'</code>
    822         * or <code>'false'</code>.</p>
    823         *
    824         * <pre>
    825         *   BooleanUtils.toStringTrueFalse(true)   = "true"
    826         *   BooleanUtils.toStringTrueFalse(false)  = "false"
    827         * </pre>
    828         *
    829         * @param bool  the Boolean to check
    830         * @return <code>'true'</code>, <code>'false'</code>,
    831         *  or <code>null</code>
    832         */
    833        public static String toStringTrueFalse(boolean bool) {
    834            return toString(bool, "true", "false");
    835        }
    836
    837        /**
    838         * <p>Converts a boolean to a String returning <code>'on'</code>
    839         * or <code>'off'</code>.</p>
    840         *
    841         * <pre>
    842         *   BooleanUtils.toStringOnOff(true)   = "on"
    843         *   BooleanUtils.toStringOnOff(false)  = "off"
    844         * </pre>
    845         *
    846         * @param bool  the Boolean to check
    847         * @return <code>'on'</code>, <code>'off'</code>,
    848         *  or <code>null</code>
    849         */
    850        public static String toStringOnOff(boolean bool) {
    851            return toString(bool, "on", "off");
    852        }
    853
    854        /**
    855         * <p>Converts a boolean to a String returning <code>'yes'</code>
    856         * or <code>'no'</code>.</p>
    857         *
    858         * <pre>
    859         *   BooleanUtils.toStringYesNo(true)   = "yes"
    860         *   BooleanUtils.toStringYesNo(false)  = "no"
    861         * </pre>
    862         *
    863         * @param bool  the Boolean to check
    864         * @return <code>'yes'</code>, <code>'no'</code>,
    865         *  or <code>null</code>
    866         */
    867        public static String toStringYesNo(boolean bool) {
    868            return toString(bool, "yes", "no");
    869        }
    870
    871        /**
    872         * <p>Converts a boolean to a String returning one of the input Strings.</p>
    873         *
    874         * <pre>
    875         *   BooleanUtils.toString(true, "true", "false")   = "true"
    876         *   BooleanUtils.toString(false, "true", "false")  = "false"
    877         * </pre>
    878         *
    879         * @param bool  the Boolean to check
    880         * @param trueString  the String to return if <code>true</code>,
    881         *  may be <code>null</code>
    882         * @param falseString  the String to return if <code>false</code>,
    883         *  may be <code>null</code>
    884         * @return one of the two input Strings
    885         */
    886        public static String toString(boolean bool, String trueString, String falseString) {
    887            return bool ? trueString : falseString;
    888        }
    889
    890        // xor methods
    891        // ----------------------------------------------------------------------
    892        /**
    893         * <p>Performs an xor on a set of booleans.</p>
    894         *
    895         * <pre>
    896         *   BooleanUtils.xor(new boolean[] { true, true })   = false
    897         *   BooleanUtils.xor(new boolean[] { false, false }) = false
    898         *   BooleanUtils.xor(new boolean[] { true, false })  = true
    899         * </pre>
    900         *
    901         * @param array  an array of <code>boolean<code>s
    902         * @return <code>true</code> if the xor is successful.
    903         * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
    904         * @throws IllegalArgumentException if <code>array</code> is empty.
    905         */
    906        public static boolean xor(boolean[] array) {
    907            // Validates input
    908            if (array == null) {
    909                throw new IllegalArgumentException("The Array must not be null");
    910            } else if (array.length == 0) {
    911                throw new IllegalArgumentException("Array is empty");
    912            }
    913
    914            // Loops through array, comparing each item
    915            int trueCount = 0;
    916            for (int i = 0; i < array.length; i++) {
    917                // If item is true, and trueCount is < 1, increments count
    918                // Else, xor fails
    919                if (array[i]) {
    920                    if (trueCount < 1) {
    921                        trueCount++;
    922                    } else {
    923                        return false;
    924                    }
    925                }
    926            }
    927
    928            // Returns true if there was exactly 1 true item
    929            return trueCount == 1;
    930        }
    931
    932        /**
    933         * <p>Performs an xor on an array of Booleans.</p>
    934         *
    935         * <pre>
    936         *   BooleanUtils.xor(new Boolean[] { Boolean.TRUE, Boolean.TRUE })   = Boolean.FALSE
    937         *   BooleanUtils.xor(new Boolean[] { Boolean.FALSE, Boolean.FALSE }) = Boolean.FALSE
    938         *   BooleanUtils.xor(new Boolean[] { Boolean.TRUE, Boolean.FALSE })  = Boolean.TRUE
    939         * </pre>
    940         *
    941         * @param array  an array of <code>Boolean<code>s
    942         * @return <code>true</code> if the xor is successful.
    943         * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
    944         * @throws IllegalArgumentException if <code>array</code> is empty.
    945         * @throws IllegalArgumentException if <code>array</code> contains a <code>null</code>
    946         */
    947        public static Boolean xor(Boolean[] array) {
    948            if (array == null) {
    949                throw new IllegalArgumentException("The Array must not be null");
    950            } else if (array.length == 0) {
    951                throw new IllegalArgumentException("Array is empty");
    952            }
    953            boolean[] primitive = null;
    954            try {
    955                primitive = ArrayUtils.toPrimitive(array);
    956            } catch (NullPointerException ex) {
    957                throw new IllegalArgumentException("The array must not contain any null elements");
    958            }
    959            return xor(primitive) ? Boolean.TRUE : Boolean.FALSE;
    960        }
    961
    962    }