When non-existing file are specified to javax.swing.URLImageIcon(URL) ,
the conection is not closed untl Socket finalize() is executed.

CONFIGURATION :
 JDK : 1.4.2_05(1.4.2_10)
 OS : Generic
 

REPRODUCE:
  
1) Compile the src code listed below.

===================================================
import javax.swing.*;
import java.net.*;
class c
{
  public static void main(String[] arg) throws Exception
  {
    URL u = new URL(arg[0]);
    new ImageIcon(u);
    while (true)
      Thread.sleep(10000);
  }
}
========================================================

2) Specify non-existing URL file

 ex.
   java c http://www.existingserver.co.jp/nonexist.gif

 when netstat is invoked, the status is
   Client side : ESTABLISHED -> CLOSE_WAIT
   Server side : ESTABLISHED -> FIN_WAIT_2

 This status is changed after the application exits.