Re: Sort Map on Value

From:
Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 09 Sep 2009 11:28:14 -0700
Message-ID:
<etSpm.179580$0e4.155012@newsfe19.iad>
Wojtek wrote:

Lew wrote :

The documentation for 'SortedMap' and 'TreeMap' very distinctly warns
that the implementations use 'compare' and 'compareTo' instead of
'equals', and very strongly advise that one keep the methods
consistent.

the equals() uses a compareTo() internally, that would be against the
key:
 


That does not pertain to what I'm saying. I'm discussing the use of
'compareTo' instead of 'equals', not by 'equals'.

  @Override
  public boolean equals( Object key )
  {
    return ivKey.equals( ((PersonMapKey) key).getKey() );
  }
 


That's all well and good, but your 'equals' is not consistent with
your implementation of 'compareTo', and therefore could raise trouble
for SortedMap implementations, according to the Javadocs.


Ok, so why is it that the interface Comparable does not also have

public boolean equals(Object o);

as part of its definition?

If you do something different inside compareTo(), then that difference
should be reflected in equals() should it not?

It would be nice, but it is not required.

--
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