Generics & Swing

December 5, 2007 · Programming

Generics & swing

Recently i wrote a debugging frame for my main Ph.D. project, a Java compiler with a extra goodies (will come to that as soon as i have a release, be patient :) ). I was surprised when i saw that the javax.swing.JList class has a constructor that takes as input a generic java.util.Vector.

JList(Vector<?> listData) 
	Constructs a JList that displays the elements in the specified Vector

I originally thought that the usage of generics are so well integrated in the java development kit, that they took the time to modify the swing components. But i was wrong. To get the value of a selected item you must use the

Object getSelectedValue()
	Returns the value for the smallest selected cell index; the selected value when only a single item is selected in the list.
Object[] getSelectedValues()
	Returns an array of all the selected values, in increasing order based on their indices in the list.

As you can see, the result is a java.lang.Object. So, if you want to program some serious (or typical) swing application, you can forget about type-safety.