Sorting a list using a comparator

Question

import java.util.*;

public class CW3 {

 private static HashMap < String, Integer > map = new HashMap < String, Integer > ();

 int comp(String s1, String s2) {
    int i1 = map.get(s1);
    int i2 = map.get(s2);
    if (i1 < i2)
    return -1 ;
    else if (i1 == i2)
    return 0;
    else 
    return 1;
}

 void sort(List l) {
     Comparator c = new Comparator() {
      public int compare(Object o1,Object o2) {   
          String a = (String)o1;
          String b = (String)o2;
          int result = new CW3().comp(a,b);
          return result;
     }
     };

   // this is where I need help
}
}

How would I use the comparator to sort the list??

I was thinking maybe something along the lines of Collections.sort(l, c)

injecteer · Accepted Answer · 2014-03-13 00:52:31Z

1

yes, you can use Collections.sort( list, comparator ) or a TreeSet which sorts the collection upon adding of new elements

SortedSet ss = new TreeSet( comparator );
ss.add( someObj0 );
.... 
ss.add( someObjn );
List sortedList = new ArrayList( ss );

answered Mar 13, 2014 at 0:52

injecteer

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Comments

DwB · Accepted Answer · 2014-03-13 00:51:43Z

0

Yes.

YourComparitorClass comparitor = new YourComparitorClass();
List<SomeType> list = ... initialize this somehow that makes sense

Collections.sort(list, comparitor);

answered Mar 13, 2014 at 0:51

DwB

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