Re: Read in & count characters from a text file

From:

ram@zedat.fu-berlin.de (Stefan Ram)

Newsgroups:

comp.lang.java.programmer

Date:

4 Aug 2007 21:22:23 GMT

Message-ID:

<autovivificate-20070804232114@ram.dialup.fu-berlin.de>

Supersedes: <autovivificate-20070804231921@ram.dialup.fu-berlin.de>

"Jay Cee" <itsjayceecee@hotmail.com> writes:

My problems seems to be I cannot "check the map" if the
character exists and if it does exist how do I get at the value
to increment it.

  You might use something like

class NumericMapUtils
{ public static <D> void addTo /* autovivificate the value to 0 */
  ( final java.util.Map<D,java.lang.Integer> map, final D d, final int i )
  { map.put( d, i +( map.containsKey( d )? map.get( d ): 0 )); }}

  and a sorted map

java.util.TreeMap<java.lang.Character,java.lang.Integer> map;

  then add each text like

NumericMapUtils.addTo<java.lang.Character>( map, 'a', 1 );
NumericMapUtils.addTo<java.lang.Character>( map, 'c', 1 );
NumericMapUtils.addTo<java.lang.Character>( map, 'n', 1 );
NumericMapUtils.addTo<java.lang.Character>( map, 'x', 1 );

  (I have not tested this. Possibly, the "<java.lang.Character>"
  type argument can be omitted.)

  Then iterate: ?for( final java.lang.Character key: map.keySet() )?

  For files of arbitrary size, use java.math.BigInteger instead
  of java.lang.Integer.

Supersedes: <autovivificate-20070804231921@ram.dialup.fu-berlin.de>