Re: Do you ever use reflection instead of OO?

Mark Space <>
Sun, 08 Jun 2008 10:30:01 -0700
Aaron Fude wrote:

The OO alternative would be to create an interface "HTMLable", but the
above approach saves the user from having to implement that on every
type of object that he might want to stick into a table. As another

Well, no.

It's easy in Java to pass interfaces without actually implementing that
interface on any object.

public class TestHtml {
   public void main( String ... args ) {
     Set s = new HashSet();
       "one two three four five six seven".split(" ")));

     Htmlizer( new HtmlTableIface() {
       public String toHtml() {
         return "<code>"+s.toString+"</code>";
     } );


   void Htmlizer ( HtmlTableIface h ) {
     System.out.println( h.toHtml() )

interface HtmlTableIface {
   String toHtml();

I didn't compile that, but you get the idea. To pass an object to a
method that takes an interface, just wrap the object in an anonymous
class. This isn't always the best, but it works for "simple situations."

In general, you want to ensure intent. Require interfaces because it's
better to push some of the work off to the caller. In your example, you
could simplify your reflection just to this:

   print( obj.toString );

And then just provide an appropriate toString method for all objects.

public class MyHtmlTableEntry {
   public String toString() {
     return "<code>"+...+"</code>";

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