hadoop-common-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Nicholas Telford (JIRA)" <j...@apache.org>
Subject [jira] Created: (HADOOP-7153) MapWritable violates contract of Map interface for equals() and hashCode()
Date Wed, 23 Feb 2011 11:00:38 GMT
MapWritable violates contract of Map interface for equals() and hashCode()
--------------------------------------------------------------------------

                 Key: HADOOP-7153
                 URL: https://issues.apache.org/jira/browse/HADOOP-7153
             Project: Hadoop Common
          Issue Type: Improvement
          Components: io
    Affects Versions: 0.21.0
            Reporter: Nicholas Telford
            Priority: Minor


o.a.h.io.MapWritable implements the java.util.Map interface, however it does not define an
implementation of the equals() or hashCode() methods; instead the default implementations
in java.lang.Object are used.

This violates the contract of the Map interface which defines different behaviour for equals()
and hashCode() than Object does. More information here: http://download.oracle.com/javase/6/docs/api/java/util/Map.html#equals(java.lang.Object)

The practical consequence is that MapWritables containing equal entries cannot be compared
properly. We were bitten by this when trying to write an MRUnit test for a Mapper that outputs
MapWritables; the MRUnit driver cannot test the equality of the expected and actual MapWritable
objects.

-- 
This message is automatically generated by JIRA.
-
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message