Boolean factory that avoids creating new Boolean objects all the time. This method was added to JDK1.4 but is available here for earlier JDKs. BooleanUtils.toBooleanObject(false) = Boolean.FALSE BooleanUtils.toBooleanObject(true) = Boolean.TRUE - Java java.lang

Description

Boolean factory that avoids creating new Boolean objects all the time. This method was added to JDK1.4 but is available here for earlier JDKs. BooleanUtils.toBooleanObject(false) = Boolean.FALSE BooleanUtils.toBooleanObject(true) = Boolean.TRUE

Demo Code

/*//from www  .  ja va  2 s.  c  om
 * 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.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        boolean bool = true;
        System.out.println(toBooleanObject(bool));
    }

    /**
     * <p>Boolean factory that avoids creating new Boolean objects all the time.</p>
     *
     * <p>This method was added to JDK1.4 but is available here for earlier JDKs.</p>
     *
     * <pre>
     *   BooleanUtils.toBooleanObject(false) = Boolean.FALSE
     *   BooleanUtils.toBooleanObject(true)  = Boolean.TRUE
     * </pre>
     *
     * @param bool  the boolean to convert
     * @return Boolean.TRUE or Boolean.FALSE as appropriate
     */
    public static Boolean toBooleanObject(boolean bool) {
        return bool ? Boolean.TRUE : Boolean.FALSE;
    }

    /**
     * <p>Converts an int to a Boolean using the convention that <code>zero</code>
     * is <code>false</code>.</p>
     *
     * <pre>
     *   BooleanUtils.toBoolean(0) = Boolean.FALSE
     *   BooleanUtils.toBoolean(1) = Boolean.TRUE
     *   BooleanUtils.toBoolean(2) = Boolean.TRUE
     * </pre>
     *
     * @param value  the int to convert
     * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero,
     *  <code>null</code> if <code>null</code>
     */
    public static Boolean toBooleanObject(int value) {
        return value == 0 ? Boolean.FALSE : Boolean.TRUE;
    }

    /**
     * <p>Converts an Integer to a Boolean using the convention that <code>zero</code>
     * is <code>false</code>.</p>
     *
     * <p><code>null</code> will be converted to <code>null</code>.</p>
     *
     * <pre>
     *   BooleanUtils.toBoolean(new Integer(0))    = Boolean.FALSE
     *   BooleanUtils.toBoolean(new Integer(1))    = Boolean.TRUE
     *   BooleanUtils.toBoolean(new Integer(null)) = null
     * </pre>
     *
     * @param value  the Integer to convert
     * @return Boolean.TRUE if non-zero, Boolean.FALSE if zero,
     *  <code>null</code> if <code>null</code> input
     */
    public static Boolean toBooleanObject(Integer value) {
        if (value == null) {
            return null;
        }
        return value.intValue() == 0 ? Boolean.FALSE : Boolean.TRUE;
    }

    /**
     * <p>Converts an int to a Boolean specifying the conversion values.</p>
     *
     * <pre>
     *   BooleanUtils.toBooleanObject(0, 0, 2, 3) = Boolean.TRUE
     *   BooleanUtils.toBooleanObject(2, 1, 2, 3) = Boolean.FALSE
     *   BooleanUtils.toBooleanObject(3, 1, 2, 3) = null
     * </pre>
     *
     * @param value  the Integer to convert
     * @param trueValue  the value to match for <code>true</code>
     * @param falseValue  the value to match for <code>false</code>
     * @param nullValue  the value to to match for <code>null</code>
     * @return Boolean.TRUE, Boolean.FALSE, or <code>null</code>
     * @throws IllegalArgumentException if no match
     */
    public static Boolean toBooleanObject(int value, int trueValue,
            int falseValue, int nullValue) {
        if (value == trueValue) {
            return Boolean.TRUE;
        } else if (value == falseValue) {
            return Boolean.FALSE;
        } else if (value == nullValue) {
            return null;
        }
        // no match
        throw new IllegalArgumentException(
                "The Integer did not match any specified value");
    }

    /**
     * <p>Converts an Integer to a Boolean specifying the conversion values.</p>
     *
     * <pre>
     *   BooleanUtils.toBooleanObject(new Integer(0), new Integer(0), new Integer(2), new Integer(3)) = Boolean.TRUE
     *   BooleanUtils.toBooleanObject(new Integer(2), new Integer(1), new Integer(2), new Integer(3)) = Boolean.FALSE
     *   BooleanUtils.toBooleanObject(new Integer(3), new Integer(1), new Integer(2), new Integer(3)) = null
     * </pre>
     *
     * @param value  the Integer to convert
     * @param trueValue  the value to match for <code>true</code>,
     *  may be <code>null</code>
     * @param falseValue  the value to match for <code>false</code>,
     *  may be <code>null</code>
     * @param nullValue  the value to to match for <code>null</code>,
     *  may be <code>null</code>
     * @return Boolean.TRUE, Boolean.FALSE, or <code>null</code>
     * @throws IllegalArgumentException if no match
     */
    public static Boolean toBooleanObject(Integer value, Integer trueValue,
            Integer falseValue, Integer nullValue) {
        if (value == null) {
            if (trueValue == null) {
                return Boolean.TRUE;
            } else if (falseValue == null) {
                return Boolean.FALSE;
            } else if (nullValue == null) {
                return null;
            }
        } else if (value.equals(trueValue)) {
            return Boolean.TRUE;
        } else if (value.equals(falseValue)) {
            return Boolean.FALSE;
        } else if (value.equals(nullValue)) {
            return null;
        }
        // no match
        throw new IllegalArgumentException(
                "The Integer did not match any specified value");
    }

    /**
     * <p>Converts a String to a Boolean.</p>
     *
     * <p><code>'true'</code>, <code>'on'</code> or <code>'yes'</code>
     * (case insensitive) will return <code>true</code>.
     * <code>'false'</code>, <code>'off'</code> or <code>'no'</code>
     * (case insensitive) will return <code>false</code>.
     * Otherwise, <code>null</code> is returned.</p>
     *
     * <pre>
     *   BooleanUtils.toBooleanObject(null)    = null
     *   BooleanUtils.toBooleanObject("true")  = Boolean.TRUE
     *   BooleanUtils.toBooleanObject("false") = Boolean.FALSE
     *   BooleanUtils.toBooleanObject("on")    = Boolean.TRUE
     *   BooleanUtils.toBooleanObject("ON")    = Boolean.TRUE
     *   BooleanUtils.toBooleanObject("off")   = Boolean.FALSE
     *   BooleanUtils.toBooleanObject("oFf")   = Boolean.FALSE
     *   BooleanUtils.toBooleanObject("blue")  = null
     * </pre>
     *
     * @param str  the String to check
     * @return the Boolean value of the string,
     *  <code>null</code> if no match or <code>null</code> input
     */
    public static Boolean toBooleanObject(String str) {
        if ("true".equalsIgnoreCase(str)) {
            return Boolean.TRUE;
        } else if ("false".equalsIgnoreCase(str)) {
            return Boolean.FALSE;
        } else if ("on".equalsIgnoreCase(str)) {
            return Boolean.TRUE;
        } else if ("off".equalsIgnoreCase(str)) {
            return Boolean.FALSE;
        } else if ("yes".equalsIgnoreCase(str)) {
            return Boolean.TRUE;
        } else if ("no".equalsIgnoreCase(str)) {
            return Boolean.FALSE;
        }
        // no match
        return null;
    }

    /**
     * <p>Converts a String to a Boolean throwing an exception if no match.</p>
     *
     * <pre>
     *   BooleanUtils.toBooleanObject("true", "true", "false", "null")  = Boolean.TRUE
     *   BooleanUtils.toBooleanObject("false", "true", "false", "null") = Boolean.FALSE
     *   BooleanUtils.toBooleanObject("null", "true", "false", "null")  = null
     * </pre>
     *
     * @param str  the String to check
     * @param trueString  the String to match for <code>true</code>
     *  (case sensitive), may be <code>null</code>
     * @param falseString  the String to match for <code>false</code>
     *  (case sensitive), may be <code>null</code>
     * @param nullString  the String to match for <code>null</code>
     *  (case sensitive), may be <code>null</code>
     * @return the Boolean value of the string,
     *  <code>null</code> if either the String matches <code>nullString</code>
     *  or if <code>null</code> input and <code>nullString</code> is
     *  <code>null</code>
     * @throws IllegalArgumentException if the String doesn't match
     */
    public static Boolean toBooleanObject(String str, String trueString,
            String falseString, String nullString) {
        if (str == null) {
            if (trueString == null) {
                return Boolean.TRUE;
            } else if (falseString == null) {
                return Boolean.FALSE;
            } else if (nullString == null) {
                return null;
            }
        } else if (str.equals(trueString)) {
            return Boolean.TRUE;
        } else if (str.equals(falseString)) {
            return Boolean.FALSE;
        } else if (str.equals(nullString)) {
            return null;
        }
        // no match
        throw new IllegalArgumentException(
                "The String did not match any specified value");
    }
}

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