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Posted to commits@harmony.apache.org by "Regis Xu (JIRA)" <ji...@apache.org> on 2009/02/11 06:45:00 UTC
[jira] Closed: (HARMONY-6076) [eut][classlib][luni] -
Arrays.sort(T[] a, Comparator c) is not stable
[ https://issues.apache.org/jira/browse/HARMONY-6076?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Regis Xu closed HARMONY-6076.
-----------------------------
Verified. Thanks Sean.
> [eut][classlib][luni] - Arrays.sort(T[] a, Comparator<? super T> c) is not stable
> ----------------------------------------------------------------------------------
>
> Key: HARMONY-6076
> URL: https://issues.apache.org/jira/browse/HARMONY-6076
> Project: Harmony
> Issue Type: Bug
> Components: Classlib
> Affects Versions: 5.0M8
> Reporter: Regis Xu
> Assignee: Sean Qiu
> Fix For: 5.0M9
>
> Attachments: HARMONY-6076.diff
>
>
> spec says "This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort."
> but Harmony's implementation is not, which cause eut failure in org.eclipse.jdt.core.tests.compiler.test074 - 1.3
> see the following test:
> public class TestArrays {
> public static void main(String[] args) {
> Element[] array = new Element[11];
> array[0] = new Element(122);
> array[1] = new Element(146);
> array[2] = new Element(178);
> array[3] = new Element(208);
> array[4] = new Element(117);
> array[5] = new Element(146);
> array[6] = new Element(173);
> array[7] = new Element(203);
> array[8] = new Element(56);
> array[9] = new Element(82);
> array[10] = new Element(96);
> for (int i = 0; i < array.length; i++) {
> System.out.println("Element value is " + array[i].getValue()
> + " index is " + array[i].getIndex());
> }
> Arrays.sort(array, new ElementComparator());
> for (int i = 0; i < array.length; i++) {
> System.out.println("Element value is " + array[i].getValue()
> + " index is " + array[i].getIndex());
> }
> }
> public static class Element {
> private int value;
> private int index;
> public int getIndex() {
> return index;
> }
> private static int count = 0;
> public int getValue() {
> return value;
> }
> public void setValue(int value) {
> this.value = value;
> }
> public Element(int value) {
> this.value = value;
> index = count++;
> }
> }
> public static class ElementComparator implements Comparator {
> public int compare(Object arg0, Object arg1) {
> return ((Element) arg0).getValue() - ((Element) arg1).getValue();
> }
> }
> }
> notice array[1] and array[5] has the same value, the indexes are 1 and 5 corresponding, after a stable sort, element has index 1 should be ahead of element has index 5
> output of RI:
> =========before sort=============
> Element value is 122 index is 0
> Element value is 146 index is 1
> Element value is 178 index is 2
> Element value is 208 index is 3
> Element value is 117 index is 4
> Element value is 146 index is 5
> Element value is 173 index is 6
> Element value is 203 index is 7
> Element value is 56 index is 8
> Element value is 82 index is 9
> Element value is 96 index is 10
> =========after sort=============
> Element value is 56 index is 8
> Element value is 82 index is 9
> Element value is 96 index is 10
> Element value is 117 index is 4
> Element value is 122 index is 0
> Element value is 146 index is 1
> Element value is 146 index is 5
> Element value is 173 index is 6
> Element value is 178 index is 2
> Element value is 203 index is 7
> Element value is 208 index is 3
> output of Harmony:
> =========before sort=============
> Element value is 122 index is 0
> Element value is 146 index is 1
> Element value is 178 index is 2
> Element value is 208 index is 3
> Element value is 117 index is 4
> Element value is 146 index is 5
> Element value is 173 index is 6
> Element value is 203 index is 7
> Element value is 56 index is 8
> Element value is 82 index is 9
> Element value is 96 index is 10
> =========after sort=============
> Element value is 56 index is 8
> Element value is 82 index is 9
> Element value is 96 index is 10
> Element value is 117 index is 4
> Element value is 122 index is 0
> Element value is 146 index is 5
> Element value is 146 index is 1
> Element value is 173 index is 6
> Element value is 178 index is 2
> Element value is 203 index is 7
> Element value is 208 index is 3
> notice that in Harmony index 1 and 5 is out of order after sort
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