[jira] [Comment Edited] (KYLIN-3581) compareTo method should be paired with equals method

["XiaoXiang Yu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KYLIN-3581?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16625468#comment-16625468 ] 

XiaoXiang Yu edited comment on KYLIN-3581 at 9/25/18 3:08 AM:
--------------------------------------------------------------

I think I can fix it.

 

My opinion:

According to java api, https://docs.oracle.com/javase/8/docs/api/ says:
{quote}_It is strongly recommended, but not strictly required that {{(x.compareTo(y)==0) == (x.equals(y))}}. Generally speaking, any class that implements the {{Comparable}} interface and violates this condition should clearly indicate this fact. The recommended language is "Note: this class has a natural ordering that is inconsistent with equals."_
{quote}
And [https://dzone.com/articles/the-hidden-contract-between-equals-and-comparable]

 

I think I should provide both implementation of equals and hashCode.Maybe I can delegate equal to  compareTo(obj) == 0.Like:
{quote}public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    MergeSlot mergeSlot = (MergeSlot) o;
    return compareTo(mergeSlot) == 0;
}
{quote}


was (Author: hit_lacus):
I think I can fix it.

> compareTo method should be paired with equals method
> ----------------------------------------------------
>
>                 Key: KYLIN-3581
>                 URL: https://issues.apache.org/jira/browse/KYLIN-3581
>             Project: Kylin
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Assignee: XiaoXiang Yu
>            Priority: Minor
>             Fix For: v2.4.2, v2.5.1
>
>
> DoggedCubeBuilder$MergeSlot and InMemCubeBuilder$CuboidTask define compareTo method.
> They should define equals method as well.



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