Re: Finding Duplicate Values In An Array List

From:
Daniele Futtorovic <da.futt.news@laposte.net>
Newsgroups:
comp.lang.java.programmer
Date:
Sat, 12 Jul 2014 16:18:37 +0200
Message-ID:
<lprg46$989$1@dont-email.me>
On 2014-07-10 19:24, Robert Klemme allegedly wrote:

On 09.07.2014 16:47, Daniele Futtorovic wrote:

Here's another, shorter one:

public static void main(String[] ss){
   Scanner sc = new Scanner(System.in);
   Set<Integer> sieve = new HashSet<Integer>();
   List<Integer> stash = new ArrayList<Integer>(20);

   while( stash.size() < 20 ){
     System.err.printf( "Enter %d more number(s) between 10 and 100:%n",
20 - stash.size() );
     String raw = sc.next();

     try {
       int input = Integer.parseInt(raw);

       if( input < 10 || input > 100 ){
         System.err.println( "Out of range: " + input );
       }
       else if( ! sieve.add( input ) ){
         System.err.println( "Duplicate: " + input );
       }
       else {
         stash.add( input );
         System.err.println( stash );
       }
     }
     catch( NumberFormatException nfex ){
       System.err.println( "Not a number: " + raw );
     }
   }


Similar amount of lines, but differently distributed

package golf;

import java.util.BitSet;
import java.util.Scanner;

public class FiDuWa {

  private static final int LIMIT = 20;
  private static final int MIN = 10;
  private static final int MAX = 100;

  public static void main(String[] args) {
    @SuppressWarnings("resource")
    final Scanner scan = new Scanner(System.in);
    final StringBuilder stash = new StringBuilder();
    final BitSet used = new BitSet();

    while (used.cardinality() < LIMIT) {
      final int i = Integer.parseInt(scan.next());

      if (i >= MIN && i <= MAX) {
        if (!used.get(i)) {
          if (!used.isEmpty())
            stash.append(' ');

          stash.append(i);
          used.set(i);
          System.out.println(stash);
        } else
          System.err.println("Duplicate: " + i);
      } else {
        System.err.println("Not in range: " + i);
      }
    }
  }
}

The Java standard library is a remarkable beast and BitSets are probably
underused.


It sure is and they may be. I reckon they do strongly appeal to
(C-family?) programmers used to bit manipulation. While I personally do
on occasion gladly indulge in the latter, it remains that I find they
lack a bit in heuristics. So while they are great tools, their place
would IMO be deep under the hood.

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