booleanutils.java

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package org.apache.commons.lang;

import org.apache.commons.lang.math.NumberUtils;

/**
 * <p>Operations on boolean primitives and Boolean objects.</p>
 *
 * <p>This class tries to handle <code>null</code> input gracefully.
 * An exception will not be thrown for a <code>null</code> input.
 * Each method documents its behaviour in more detail.</p>
 * 
 * @author Stephen Colebourne
 * @author Matthew Hawthorne
 * @author Gary Gregory
 * @since 2.0
 * @version $Id: BooleanUtils.java,v 1.14 2003/08/22 17:25:33 ggregory Exp $
 */
public class BooleanUtils {

    /**
     * <p><code>BooleanUtils</code> instances should NOT be constructed in standard programming.
     * Instead, the class should be used as <code>BooleanUtils.toBooleanObject(true);</code>.</p>
     *
     * <p>This constructor is public to permit tools that require a JavaBean instance
     * to operate.</p>
     */
    public BooleanUtils() {
    }

    // Boolean utilities
    //--------------------------------------------------------------------------
    /**
     * <p>Negates the specified boolean.</p>
     * 
     * <p>If <code>null</code> is passed in, <code>null</code> will be returned.</p>
     * 
     * @param bool  the Boolean to negate, may be null
     * @return the negated Boolean, or <code>null</code> if <code>null</code> input
     */
    public static Boolean negate(Boolean bool) {
        if (bool == null) {
            return null;
        }
        return (bool.booleanValue() ? Boolean.FALSE : Boolean.TRUE);
    }
    
    // boolean Boolean methods
    //-----------------------------------------------------------------------
    /**
     * <p>Boolean factory that avoids creating new Boolean objecs all the time.</p>
     * 
     * <p>This method was added to JDK1.4 but is available here for earlier JDKs.</p>
     * 
     * @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 a Boolean to a boolean handling <code>null</code>
     * by returning <code>false</code>.</p>
     * 
     * @param bool  the boolean to convert
     * @return <code>true</code> or <code>false</code>, 
     *  <code>null</code> returns <code>false</code>
     */
    public static boolean toBoolean(Boolean bool) {
        if (bool == null) {
            return false;
        }
        return (bool.booleanValue() ? true : false);
    }
    
    /**
     * <p>Converts a Boolean to a boolean handling <code>null</code>.</p>
     * 
     * @param bool  the boolean to convert
     * @param valueIfNull  the boolean value to return if <code>null</code>
     * @return <code>true</code> or <code>false</code>
     */
    public static boolean toBooleanDefaultIfNull(Boolean bool, boolean valueIfNull) {
        if (bool == null) {
            return valueIfNull;
        }
        return (bool.booleanValue() ? true : false);
    }
    
    // Integer to Boolean methods
    //-----------------------------------------------------------------------
    /**
     * <p>Converts an int to a boolean using the convention that <code>zero</code>
     * is <code>false</code>.</p>
     * 
     * @param value  the int to convert
     * @return <code>true</code> if non-zero, <code>false</code>
     *  if zero
     */
    public static boolean toBoolean(int value) {
        return (value == 0 ? false : true);
    }
    
    /**
     * <p>Converts an int to a Boolean using the convention that <code>zero</code>
     * is <code>false</code>.</p>
     * 
     * @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>
     * 
     * @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>
     * 
     * @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>
     * @return <code>true</code> or <code>false</code>
     * @throws IllegalArgumentException if no match
     */
    public static boolean toBoolean(int value, int trueValue, int falseValue) {
        if (value == trueValue) {
            return true;
        } else if (value == falseValue) {
            return false;
        }
        // no match
        throw new IllegalArgumentException("The Integer did not match either specified value");
    }
    
    /**
     * <p>Converts an Integer to a boolean specifying the conversion values.</p>
     * 
     * @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>
     * @return <code>true</code> or <code>false</code>
     * @throws IllegalArgumentException if no match
     */
    public static boolean toBoolean(Integer value, Integer trueValue, Integer falseValue) {
        if (value == null) {
            if (trueValue == null) {
                return true;
            } else if (falseValue == null) {
                return false;
            }
        } else if (value.equals(trueValue)) {
            return true;
        } else if (value.equals(falseValue)) {
            return false;
        }
        // no match
        throw new IllegalArgumentException("The Integer did not match either specified value");
    }
    
    /**
     * <p>Converts an int to a Boolean specifying the conversion values.</p>
     * 
     * @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>
     * 
     * @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");
    }
    
    // Boolean to Integer methods
    //-----------------------------------------------------------------------
    /**
     * <p>Converts a boolean to an int using the convention that
     * <code>zero</code> is <code>false</code>.</p>
     * 
     * @param bool  the boolean to convert
     * @return one if <code>true</code>, zero if <code>false</code>
     */
    public static int toInteger(boolean bool) {
        return (bool ? 1 : 0);
    }
    
    /**
     * <p>Converts a boolean to an Integer using the convention that
     * <code>zero</code> is <code>false</code>.</p>
     * 
     * @param bool  the boolean to convert
     * @return one if <code>true</code>, zero if <code>false</code>
     */
    public static Integer toIntegerObject(boolean bool) {
        return (bool ? NumberUtils.INTEGER_ONE : NumberUtils.INTEGER_ZERO);
    }
    
    /**
     * <p>Converts a Boolean to a Integer using the convention that
     * <code>zero</code> is <code>false</code>.</p>
     * 
     * <p><code>null</code> will be converted to <code>null</code>.</p>
     * 
     * @param bool  the Boolean to convert
     * @return one if Boolean.TRUE, zero if Boolean.FALSE, <code>null</code> if <code>null</code>
     */
    public static Integer toIntegerObject(Boolean bool) {
        if (bool == null) {
            return null;
        }
        return (bool.booleanValue() ? NumberUtils.INTEGER_ONE : NumberUtils.INTEGER_ZERO);
    }
    
    /**
     * <p>Converts a boolean to an int specifying the conversion values.</p>
     * 
     * @param bool  the to convert
     * @param trueValue  the value to return if <code>true</code>
     * @param falseValue  the value to return if <code>false</code>
     * @return the appropriate value
     */
    public static int toInteger(boolean bool, int trueValue, int falseValue) {
        return (bool ? trueValue : falseValue);
    }
    
    /**