Re: HashMap problem: insert with hash code retrieve by index

From:
Lew <lew@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 27 Apr 2008 17:43:13 -0400
Message-ID:
<jtednegeoYnsbonVnZ2dnUVZ_g2dnZ2d@comcast.com>
Royan wrote:

Lets say we have the following class

public class Foo {
    private Map<Integer, String> dataMap = new HashMap<Integer,
String>();

    public String getValueAt(int idx) {
        // I wish I don't use for loop here ...
    }


This part is doable. You shouldn't include implementation in variable names.

    public void addValue(String s) {
        String l = dataMap.put(getHashCode(s), s);
    }
}


This part will always have a finite risk of failure.

You have the right Map definition. Bear in mind that only *one* Integer of
any given value can key the Map, and so if two Strings have the same
hashCode(), you'll lose one of them. That said,

<untested_example>

public class Foo
{
  private final Map <Integer, String> data =
     new HashMap <Integer, String> ();

  public String put( String val )
  {
   return data.put( val.hashCode(), val );
  }

  public String get( Integer key )
  {
   return data.get( key );
  }
}
</untested_example>

As you can see, the class is a very thin cover for Map <Integer, String>.

--
Lew

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