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From "Li Lu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (YARN-3276) Fix NPE and refactor in some map cast for TimelineEntity
Date Fri, 27 Feb 2015 22:28:05 GMT

    [ https://issues.apache.org/jira/browse/YARN-3276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14340940#comment-14340940
] 

Li Lu commented on YARN-3276:
-----------------------------

Hi [~djp], a quick question (w.r.t YARN-3087), why this line will cause a NPE?

bq. this.info = (HashMap<String, Object>) info;  // Here we can have NPE if info is
null

If info is null, we may still cast it to a HashMap, according to Java language specification
(http://docs.oracle.com/javase/specs/jls/se7/html/jls-5.html#jls-5.1.8 in Section 5.2, "A
value of the null type (the null reference is the only such value) may be assigned to any
reference type, resulting in a null reference of that type."). Am I missing something here?

I agree that we should have this refactor even if our current code does not throw NPEs. The
new approach looks much nicer. 

> Fix NPE and refactor in some map cast for TimelineEntity
> --------------------------------------------------------
>
>                 Key: YARN-3276
>                 URL: https://issues.apache.org/jira/browse/YARN-3276
>             Project: Hadoop YARN
>          Issue Type: Sub-task
>          Components: timelineserver
>            Reporter: Junping Du
>            Assignee: Junping Du
>         Attachments: YARN-3276-v2.patch, YARN-3276.patch
>
>
> Per discussion in YARN-3087, we need to refactor some similar logic to cast map to hashmap
and get rid of NPE issue.



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