Re: [Simple-support] erialize/deserialize Lists with empty Strings

[Joe <fis...@ya...>]

Hi,

> So it looks like if you really need the empty string
> "" then you will need to either treat null as a special case, or
> substitute "" for some token such as "NULL".
I think i will use a slightly different approach, inspired by the base64 
encoding example in your tutorial.
I encode every value with a prefix (here '*') only null values are ignored.

So
Arrays.asList("A", "", null)

will be serialized as:

<testData>
  <_values class="java.util.Arrays$ArrayList">
     <string>*A</string>
     <string>*</string>
     <string></string>
  </_values>
</testData>

Using @Commit the deserialization can be adjusted, to getting back
the original values.

The output of the following example is the expected String:
values: [A, , null]

public class TestData
{
   @ElementList()
   private List<String> _values = new ArrayList<String>();

   public List<String> getValues()
   {
       return _values;
   }

   public void setValues(List<String> values)
   {
       _values = values;
   }

   @Persist
   public void persist()
   {
       for (int i = 0; i < _values.size(); i++)
           if (_values.get(i) != null)
               _values.set(i, "*" + _values.get(i));
           else
               _values.set(i, "");
   }

   @Commit
   public void commit()
   {
       for (int i = 0; i < _values.size(); i++)
       {
           String val = _values.get(i);
           if (val != null)
               _values.set(i, _values.get(i).substring(1));
       }
   }
   public static void main(String[] args) throws Exception
   {
       Serializer serializer = new Persister();
       File xmlFile = new File("test.xml");
       TestData data = new TestData();
       data.setValues(Arrays.asList("A", "", null));
       serializer.write(data, xmlFile);
       TestData sqlData = serializer.read(TestData.class, xmlFile);
       System.out.println("values: " + sqlData.getValues());
   }
}