Re: [Simple-support] How can I serialize an unmodifiable list?

[Niall G. <gal...@ya...>]

I need the full stack trace here to help with this.

--- On Wed, 28/11/12, Lecomte, J-Francois <JFL...@rh...> wrote:

> From: Lecomte, J-Francois <JFL...@rh...>
> Subject: [Simple-support] How can I serialize an unmodifiable list?
> To: "sim...@li..." <sim...@li...>
> Received: Wednesday, 28 November, 2012, 5:02 PM
> 
> 
>  
>  
> 
> 
> 
> 
> I get a
> « NoSuchMethodException » when I try
> to serialize a list that is wrapped by
> Collections.unmodifiableList(…) or a list obtained by
> Arrays.asList(…). The same applies to UnmodifiableList
> from Google’s Guava library. 
> 
>   
> Here is
> a snippet that exposes the problem: 
> 
>   
> public
> class
> Main 
> { 
>    
> public
> static
> void
> main(final
>  String[] args) throws
> Exception 
>    
> { 
>        
> final
> ArrayList<Integer> arrayList =
> new
> ArrayList<Integer>(Arrays.asList(1, 2, 3,
> 4)); 
> 
>   
>        
> testLoadSave(new
> ObjectToPersist(arrayList)); // Will be successful
>  
>        
> testLoadSave(new
> ObjectToPersist(Collections.unmodifiableList(arrayList)));
>  // Will throw a NoSuchMethodException 
>        
> testLoadSave(new
> ObjectToPersist(Arrays.asList(5, 6, 7,
> 8))); 
>    
> } 
> 
>   
>    
> private
> static
> void
> testLoadSave(final
>  ObjectToPersist objectToPersist) throws
> Exception 
>    
> { 
>        
> final
> Serializer serializer =
> new
> Persister(); 
> 
>   
>        
> final
> ByteArrayOutputStream out =
> new
> ByteArrayOutputStream(); 
>        
> serializer.write(objectToPersist,
> out); 
> 
>   
>        
> final
> ByteArrayInputStream in =
> new
> ByteArrayInputStream(out.toByteArray()); 
>        
> final
> ObjectToPersist objectRead = serializer.read(ObjectToPersist.class,
>  in); 
> 
>   
>        
> System.out.println(objectRead); 
>    
> } 
> 
>   
>    
> public
> static
> class
> ObjectToPersist 
>    
> { 
>        
> @ElementList(name
> =
> "myList",
> entry =
> "element") 
>        
> private
> final
> List<Integer>
> _myList; 
> 
>   
>        
> public
> ObjectToPersist( 
>            
> @ElementList(name
> =
> "myList",
> entry =
> "element")
> final
> List<Integer> myList) 
>        
> { 
>            
> _myList
> = myList; 
>        
> } 
> 
>   
>        
> public
> List<Integer> getMyList() 
>        
> { 
>            
> return
> _myList; 
>        
> } 
> 
>   
>        
> @Override 
>        
> public
> String toString() 
>        
> { 
>            
> final
> StringBuilder builder =
> new
> StringBuilder(); 
>            
> builder.append("ObjectToPersist@"); 
>            
> builder.append(hashCode()); 
>            
> builder.append("[_myList="); 
>            
> builder.append(_myList); 
>            
> builder.append("]"); 
>            
> return
> builder.toString(); 
>        
> } 
>    
> } 
> } 
> 
>   
> 
>   
> I
> don’t really care about the exact type of the list
> stored in my object, but I would like to keep it
> unmodifiable. So far I fixed the problem by modifying
> “ObjectToPersist” class this way: 
> 
>   
>        
> public
> ObjectToPersist( 
>            
> @ElementList(name
> =
> "myList",
> entry =
> "element")
> final
> List<Integer> myList) 
>        
> { 
>            
> _myList
> =
> new
> ArrayList<Integer>(myList); 
>        
> } 
>        
> public
> List<Integer> getMyList() 
>        
> { 
>            
> return
> Collections.unmodifiableList(_myList); 
>        
> } 
> 
>   
> 
>   
> But
> this implies creating a new ArrayList all the time. I would
> prefer something like this: 
> 
>   
>        
> public
> ObjectToPersist( 
>            
> @ElementList(name
> =
> "myList",
> entry =
> "element")
> final
> List<Integer> myList) 
>        
> { 
>            
> if
> (myList is already immutable) 
>                
> _myList
> = myList; 
>            
> else 
>                
> _myList
> =
> new
> ArrayList<Integer>(myList); 
>        
> } 
>        
> public
> List<Integer> getMyList() 
>        
> { 
>            
> return
> _myList; 
>        
> } 
> 
>   
> Using
> ImmutableList from Google’s Guava library, I could do
> just this (ImmutableList.copyOf(…)), but it
> won’t serialize… I was wondering if there was a
> way to support those immutable collections with
> SimpleXML… 
> 
>   
> Thanks! 
> JFL 
> 
> 
> 
> 
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