Add size() from GroupImpl to Group please

[GoogleCodeExporter]

Following on from http://code.google.com/p/lambdaj/issues/detail?id=36,  I'm 
100% sure I want size() rather than getSize() for my case.

I initially coded for getSize() but saw unexpected results for the scenario I 
was following.  In the debugger, I saw that size() was giving the correct 
results (and different to getSize()). 

I'm thinking you won't believe me until I upload a failing tests case right ?

Original issue reported on code.google.com by PaulHamm...@gmail.com on 30 Aug 2010 at 8:31

[GoogleCodeExporter]

Hi Paul,

of course I have no reason to not believe in you. Indeed the scenario you are 
experiencing is very worrying. If what you are reporting is true (and once 
again I haven't any reason to think the opposite), you can imagine that should 
be unbearable to have an interface with both the size() and getSize() methods 
that even worse return 2 different values. And I also cannot safely remove the 
getSize() method without breaking the backward compatibility. I am not saying I 
don't want to do that at all, but I need a very good reason to do that. I hope 
you can agree.

Since I am also very curious of what you found and also to properly write an 
unit test for this issue, I'd be glad if you could give me a bit more details 
about it.

Thanks a lot
Mario

Original comment by mario.fu...@gmail.com on 30 Aug 2010 at 9:09

[GoogleCodeExporter]

// both of these fail.

package ch.lambdaj;

import ch.lambdaj.demo.Person;
import ch.lambdaj.group.Group;
import org.junit.Test;

import static ch.lambdaj.Lambda.by;
import static ch.lambdaj.Lambda.group;
import static ch.lambdaj.Lambda.on;
import static java.util.Arrays.asList;
import static junit.framework.Assert.assertEquals;

public class GroupsVarianceTest {

    private Person mario1 = new Person("Mario", "Fusco", true, "01/01/1999" );
    private Person peter = new Person("Peter", "Pan", true, "02/02/1999" );
    private Person mario2 = new Person("Mario", "Two", true, "04/04/1999");

    @Test
    public void oneGroupsRecognizedSuggestingNoVariance() {
        Group<Person> grp = group(asList(mario1, mario2), by(on(Person.class).getFirstName()));
        assertEquals(1, grp.getSize());
    }

    @Test
    public void twoGroupsRecognizedSuggestingVariance() {
        Group<Person> grp = group(asList(mario1, peter, mario2), by(on(Person.class).getFirstName()));
        assertEquals(2, grp.getSize());
    }

}

// I must be misunderstanding the doco.. my apologies of this is the case.

Original comment by PaulHamm...@gmail.com on 30 Aug 2010 at 11:27

[GoogleCodeExporter]

The interesting thing about this, is that as you gaze at 'grp' in the debugger, 
the toString() is reporting the right numbers - "size = 1" for the first test 
and "size = 2" for the second.

Original comment by PaulHamm...@gmail.com on 31 Aug 2010 at 4:21

[GoogleCodeExporter]

Well our problem was new useritis.

What we really wanted was either 

   grp.subgroups().size()

or

   grp.keySet().size()

We found that the unit tests as you have them, have one example that shows 
this.  Perhaps the Group.getSize() javadoc could be changed to:

       /**
     * Returns how many items are present in this group, wherever they are in the implicit tree-map
     */

Original comment by PaulHamm...@gmail.com on 2 Sep 2010 at 12:49

[GoogleCodeExporter]

Yes, the problem was caused in a misunderstanding in the documentation. The 
javadoc of the getSize() method has been updated as per your suggestion.

Original comment by mario.fu...@gmail.com on 16 Sep 2010 at 10:56

• Changed state: Invalid