Re: Create a JAVA Client/Server app in 5 Minutes

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 14 Apr 2009 12:11:46 -0700 (PDT)

Message-ID:

<82ab6f10-b38b-4bfd-b593-995162006fcd@n4g2000vba.googlegroups.com>

Lew did not write:

Oh, you have nested lists. It's slightly different here:

private List<? extends List<String>> data;

That was Andreas Leitgeb. Please be careful with your attributions.

Donkey Hottie wrote:

Why not just

private List<List<String>> data = new ArrayList<List<String>>() ;

See my reply upthread:

The difference is that Andreas's suggested form

private List <? extends List <String>> data =
new ArrayList <? extends List <String>> ();

requires that all nested 'List's be of the same concrete type, and the
way without 'extends' allows each outer 'List' element to be a
different concrete kind of 'List'.

I made a mistake there, though. It should have been
private List <? extends List <String>> data =
    new ArrayList <List <String>> ();

or
private List <? extends List <String>> data =
    new ArrayList <ArrayList <String>> ();

vs.
private List <List <String>> data =
    new ArrayList <List <String>> ();

The "? extends" syntax version is not permitted in a 'new' expression.

--
Lew