On Dec 30, 12:25 pm, Roedy Green <see_webs...@mindprod.com.invalid>
wrote:

There might be a way.  I think the following code performs a similar
function to what you are trying to achieve.  The code compiles without
warnings or errors and it runs correctly.  Nonetheless, it leaves
something to be desired.

import java . io . * ;
import java . util . * ;

class test
{
 public static void main ( String [ ] args ) throws Exception
 {
   ObjectInputStream ois = setupExample ( args ) ;
   runExample ( ois ) ;
 }

 /**
  * This just sets up the example.
  * It returns an appropriate ObjectInputStream
  * (i.e. one that has been stuffed with an ArrayList.
  **/
 private static ObjectInputStream setupExample ( String [ ] args )
   throws Exception
 {
   ArrayList < String > list = new ArrayList < String > ( ) ;
   for ( int i = 0 ; i < args . length ; i ++ )
     {
       list . add ( args [ i ] ) ;
     }
   ByteArrayOutputStream bos = new ByteArrayOutputStream ( ) ;
   ObjectOutputStream oos = new ObjectOutputStream ( bos ) ;
   oos . writeObject ( list ) ;
   oos . close ( ) ;
   bos . close ( ) ;
   byte [ ] b = bos . toByteArray ( ) ;
   ByteArrayInputStream bis = new ByteArrayInputStream ( b ) ;
   ObjectInputStream ois = new ObjectInputStream ( bis ) ;
   return ( ois ) ;
 }

 /**
  * This is the example.
  * We think that there is an ArrayList<java.lang.String> in
  * the InputStream.
  * How to cast it out without throwing warnings?
  **/
 private static void runExample ( ObjectInputStream ois ) throws
Exception
 {
   Object object = ois . readObject ( ) ;
   ArrayList list1 = ( ArrayList ) ( object ) ;
   ArrayList < String > list2 = nowarningCast ( String . class ,
list1 ) ;
   for ( String string : list2 )
     {
       System . out . println ( string ) ;
     }
 }

 /**
  * This is how I cast the ArrayList to
  * an ArrayList<java.lang.String> without
  * casting warnings.
  *
  * Take heed that this is not safe.
  **/
 private static < R > ArrayList < R > nowarningCast
   ( Class < R > clazz , ArrayList in )
 {
   ArrayList < R > out = new ArrayList < R > ( ) ;
   for ( Object val : in )
     {
       R r = clazz . cast ( val ) ;
       out . add ( r ) ;
     }
   return ( out ) ;
 }
}

Emory Merryman
External Concepts Guild