Hi, I have this class:

public class Converter
{
    private Logger logger = Logger.getLogger(Converter.class);
    public String convert(String s){ 
         if (s == null) throw new IllegalArgumentException("input can't be null");
         logger.debug("Input = " + s);
         String r = s + "abc";
         logger.debug("Output = " + s);
         return r;
    }

    public Integer convert(Integer s){
         if (s == null) throw new IllegalArgumentException("input can't be null");
         logger.debug("Input = " + s);
         Integer r = s + 10;
         logger.debug("Output = " + s);
         return r;
    }
}

The above 2 methods are very similar so I want to create a template to do the similar things and delegate the actual work to the approriate class. But I also want to easily extends this frame work without changing the template. So for example:

public class ConverterTemplate
{
    private Logger logger = Logger.getLogger(Converter.class);
    public Object convert(Object s){ 
         if (s == null) throw new IllegalArgumentException("input can't be null");
         logger.debug("Input = " + s);
         Object r = doConverter();
         logger.debug("Output = " + s);
         return r;
    }

    protected abstract Object doConverter(Object arg);
}

public class MyConverter extends ConverterTemplate
{
    protected String doConverter(String str)
    {
       String r = str + "abc";
       return r;
    }

    protected Integer doConverter(Integer arg)
    {
       Integer r = arg + 10;
       return r;
    }
}

But that doesn't work. Can anybody suggest me a better way to do that? I want to achieve 2 goals: 1. A template that is extensible and does all the similar work for me. 2. I ant to minimize the number of extended class.

Thanks,