[jira] [Commented] (LANG-922) Add isOneTrue(booleans...) to BooleanUtils to preserve old behavior of BooleanUtils.xor(booleans...)

["Benedikt Ritter (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LANG-922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13795492#comment-13795492 ] 

Benedikt Ritter commented on LANG-922:
--------------------------------------

Sample implementation:

{code:java}

    /**
     * <p>Checks if exactly one of the given booleans is true.</p>
     *
     * <pre>
     *   BooleanUtils.xor(true, true)   = false
     *   BooleanUtils.xor(false, false) = false
     *   BooleanUtils.xor(true, false)  = true
     *   BooleanUtils.xor(true, true)   = false
     *   BooleanUtils.xor(false, false) = false
     *   BooleanUtils.xor(true, false)  = true
     * </pre>
     *
     * @param array  an array of {@code boolean}s
     * @return {@code true} if the array only contained true once.
     * @throws IllegalArgumentException if {@code array} is {@code null}
     * @throws IllegalArgumentException if {@code array} is empty.
     * @since 3.2
     */
    public static boolean isOneTrue(final boolean... array) {
        // Validates input
        if (array == null) {
            throw new IllegalArgumentException("The Array must not be null");
        }
        if (array.length == 0) {
            throw new IllegalArgumentException("Array is empty");
        }

        // Loops through array, comparing each item
        int trueCount = 0;
        for (final boolean element : array) {
            // If item is true, and trueCount is < 1, increments count
            // Else, xor fails
            if (element) {
                if (trueCount < 1) {
                    trueCount++;
                } else {
                    return false;
                }
            }
        }

        // Returns true if there was exactly 1 true item
        return trueCount == 1;
    }

{code}

> Add isOneTrue(booleans...) to BooleanUtils to preserve old behavior of BooleanUtils.xor(booleans...)
> ----------------------------------------------------------------------------------------------------
>
>                 Key: LANG-922
>                 URL: https://issues.apache.org/jira/browse/LANG-922
>             Project: Commons Lang
>          Issue Type: Bug
>          Components: lang.*
>            Reporter: Benedikt Ritter
>             Fix For: 3.2
>
>
> The old implementation (prior to r1532476) of BooleanUtils.xor(boolean...) checked if the provided array contained exactly one boolean with value true. This was changed because it is not the correct behavior for an XOR operation. To preserve the behavior we should add BooleanUtils.isOneTrue(boolean...) and BooleanUtils.isOneTrue(Boolean...) (and possibly the equivalents for isOneFalse).



--
This message was sent by Atlassian JIRA
(v6.1#6144)