How to make component listen for a specific event of another component

Question

for example, i have several buttons and want them listen for a TreeSelectionEvent... in case anything selected they become active
i don't want a JTree component activate these buttons...

Answer 1

here's an overkill,
import java.util.*;
abstract class DoWhatever {
    public static Hashtable ht = null;
    public static Object DoWhat( String s, Object obj ) {
     if( null == ht ) {
         ht = new Hashtable();
         ht.put( ThisDoWhatever.NAME, new ThisDoWhatever() );
         ht.put( ThatDoWhatever.NAME, new ThatDoWhatever() );        
     return ( (DoWhatever) ht.get( s ) ).doWhatever( obj );
    public abstract Object doWhatever( Object obj );
class ThisDoWhatever extends DoWhatever {
    public final static String NAME = "this";
    public Object doWhatever( Object obj ) {
     System.out.println( NAME );
     return null;
class ThatDoWhatever extends DoWhatever {
    public final static String NAME = "that";
    public Object doWhatever( Object obj ) {
     System.out.println( NAME );
     return null;
public class DoThisOrThat {
    public static void main( String[] args ) {
     DoWhatever.DoWhat( args[ 0 ], null );
}