Re: HashMap get/put

From:

Wojtek <nowhere@a.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 29 Oct 2009 08:25:42 -0700

Message-ID:

<mn.e9f97d9aca78a62c.70216@a.com>

Stefan Ram wrote :

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

Look at the following example: (...)
final java.util.Map<java.lang.String,java.lang.String> value0
= new java.util.HashMap<java.lang.String,java.lang.String>(); (...)
?value1? has not the type used in the map, yet the ?get? succeeds.

  Above, both types were the same after type erasure and were
  types of empty containers.

  Here is a program with types that differ even after type
  erasure and non-empty containers.

Um, I did a bit of editing in your example, removing the packages. For
some reason this makes it easier for me to read...

public class Main
{ public static void main( final String[] args )
  {
    final ArrayList<String> list0 = new ArrayList<String >();
    list0.add( "text" );

    final LinkedList<String > list1 = new LinkedList<String >();
    list1.add( "text" );

    final Map<ArrayList<String>,String> map = new
HashMap<ArrayList<String>,String >();

    map.put( list0, "value" );

    System.out.println( map.get( list1 ));
   }
}

I do not see why this works or why this should work. Maybe because
"text" was added to both list0 and list1?

--
Wojtek :-)