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https://issues.apache.org/jira/browse/LANG-536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12764950#action_12764950
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Paul Benedict commented on LANG-536:
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Arrays.asList() allows a thin wrapper to convert an array to a list. I think
this kind of checking should move directly into ListUtils in Commons
Collections.
> Add isSorted() to ArrayUtils
> ----------------------------
>
> Key: LANG-536
> URL: https://issues.apache.org/jira/browse/LANG-536
> Project: Commons Lang
> Issue Type: New Feature
> Reporter: Sergei Ivanov
> Priority: Minor
> Fix For: 3.0
>
>
> In my unit tests I often need to verify that an array is correctly sorted.
> In order to achieve this, I've got two helper methods as follows.
> Is it possible to integrate these methods into ArrayUtils?
> {code}
> /**
> * Checks that the specified array of objects is in an ascending order
> * according to the specified comparator. All elements in the array must
> be
> * <i>mutually comparable</i> by the specified comparator (that is,
> * <tt>c.compare(e1, e2)</tt> must not throw a <tt>ClassCastException</tt>
> * for any elements <tt>e1</tt> and <tt>e2</tt> in the array).
> *
> * @param a the array to be checked.
> * @param c the comparator to determine the order of the array. A
> * <tt>null</tt> value indicates that the elements'
> * {...@linkplain Comparable natural ordering} should be used.
> * @return {...@code true}, if the array is sorted; {...@code false},
> otherwise.
> * @throws ClassCastException if the array contains elements that are
> * not <i>mutually comparable</i> using the specified comparator.
> */
> public static <T> boolean isSorted(final T[] a, final Comparator<? super
> T> c) {
> if (a.length <= 1) {
> // Empty or singleton arrays are always sorted
> return true;
> }
> // Otherwise, check that every element is not smaller than the
> previous
> T previous = a[0];
> for (int i = 1, n = a.length; i < n; i++) {
> final T current = a[i];
> if (c.compare(previous, current) > 0) {
> return false;
> }
> previous = current;
> }
> return true;
> }
> /**
> * Checks that the specified array of objects is in an ascending order,
> * according to the {...@linkplain Comparable natural ordering} of its
> elements.
> * All elements in the array must implement the {...@link Comparable}
> interface.
> * Furthermore, all elements in the array must be <i>mutually
> comparable</i>
> * (that is, <tt>e1.compareTo(e2)</tt> must not throw a
> <tt>ClassCastException</tt>
> * for any elements <tt>e1</tt> and <tt>e2</tt> in the array).
> *
> * @param a the array to be checked.
> * @return {...@code true}, if the array is sorted; {...@code false},
> otherwise.
> * @throws ClassCastException if the array contains elements that are not
> * <i>mutually comparable</i> (for example, strings and integers).
> */
> @SuppressWarnings({"unchecked"})
> public static <T> boolean isSorted(final T[] a) {
> if (a.length <= 1) {
> // Empty or singleton arrays are always sorted
> return true;
> }
> // Otherwise, check that every element is not smaller than the
> previous
> T previous = a[0];
> for (int i = 1, n = a.length; i < n; i++) {
> final T current = a[i];
> if (((Comparable<? super T>) previous).compareTo(previous) > 0) {
> return false;
> }
> previous = current;
> }
> return true;
> }
> {code}
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