gistfile1.java

public class ConverterGridDataSource implements GridDataSource {
  private final GridDataSource delegate;
  private final Converter converter;
  
  public ConverterGridDataSource(GridDataSource delegate, Converter converter) {
    this.delegate = delegate;
    this.converter = converter;
  }
  
  public int getAvailableRows() {
    return delegate.getAvailableRows();
  }
  
  public void prepare(int startIndex, int endIndex, List<SortConstraint> sortConstraints) {
    delegate.prepare(startIndex, endIndex, sortConstraints);
  }
  
  public Object getRowValue(int index) {
    return converter.convert(delegate.getRowValue(index));
  }
  
  public Class getRowType() {
    return converter.getType();
  }
}

public interface Converter<T> {
  T convert(Object o);
  Class<T> getType();
}