After 2nd time running a method my app window freezes 7 seocnds,error msg-

Question

Hello folks,
first you will surely say is that my server is offline or something with the network is wrong but it is not ;-)
thats the code:
Please read my words after the pasted code at the bottom of the page!
import java.awt.Color;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.naming.directory.*;
import javax.naming.ldap.LdapName;
import javax.naming.ldap.Rdn;
import java.util.Hashtable;
import javax.naming.Context;
import javax.naming.*;
import java.io.UnsupportedEncodingException;
import java.util.*;
import javax.swing.BorderFactory;
public class MainWindow extends JFrame implements ActionListener
       static final long serialVersionUID = 1L; 
       private JLabel newPasswordLB      = new JLabel("Neues Passwort");
     private JLabel newPasswordRepeatLB = new JLabel("Neues Passwort wiederholen");
     private JLabel errorLB = new JLabel("Fehlerstatus:");
     private JLabel benutzerNameLB = new JLabel("Benutzername ausw�hlen:");
     private JPasswordField neuesKennwortPF = new JPasswordField();
     private JPasswordField neuesKennwortWdhPF = new JPasswordField(10);
     //private JLabel fehlerNachrichtLB = new JLabel();
     private JTextField fehlerNachrichtLB = new JTextField();
     private JButton pwBT = new JButton("Setze neues Passwort");     
     private DefaultListModel listModel = new DefaultListModel();
     private JList liste = new JList(listModel);
     private JScrollPane benutzerListeSP = new JScrollPane(liste);
     private JCheckBox kennwortVergebenCB = new JCheckBox("Benutzer vergibt Kennwort bei Neuanmeldung selbst");
     JFrame frame;
     String bla;
     String neuesKennwortTemp;
     String benutzername;     
     String klassengruppe;  // OU=Klassen
     String lehrergruppe;   // OU=Lehrer
     String edvlehrername;  // z.B. "verenabit"
     String schulname;      // z.B. OU=ASR
     String BaseDN=",DC=bodensee,DC=de";
     String adminPassword = "test";
     String adminUser = "cn=administrator,cn=users,dc=bodensee,dc=de";     
     public MainWindow()
         super("LDAP Modification Tool");            
         setLayout(null);         
         add(newPasswordLB);
         add(newPasswordRepeatLB);     
         add(neuesKennwortWdhPF);
         add(neuesKennwortPF);              
         add(pwBT);       
         add(errorLB);
         add(fehlerNachrichtLB); 
         add(benutzerListeSP);        
         add(benutzerNameLB);
         add(kennwortVergebenCB);    
         kennwortVergebenCB.setBounds(16,120,350,25);
         benutzerNameLB.setBounds(430,25,160,25);    
         fehlerNachrichtLB.setOpaque(true);
         fehlerNachrichtLB.setBackground(new Color(255,255,255));
         fehlerNachrichtLB.setBorder(BorderFactory.createLineBorder(new Color(155,155,155)));
         neuesKennwortPF.setBounds(230,50,150,25);
         neuesKennwortWdhPF.setBounds(230,80,150,25);
         newPasswordLB.setBounds(20,50,130,25);
         newPasswordRepeatLB.setBounds(20,80,190,25);       
         pwBT.setBounds(230,170,150,40);             
         errorLB.setBounds(20,385,100,25);
         fehlerNachrichtLB.setBounds(110,385,270,25);       
         benutzerListeSP.setBounds(430,50,160,360);
         kennwortVergebenCB.setHorizontalTextPosition(SwingConstants.LEADING);     
         neuesKennwortPF.setMargin(new Insets(1, 3, 1, 1));
         neuesKennwortWdhPF.setMargin(new Insets(1, 3, 1, 1));        
         pwBT.setMargin(new Insets(0,0,0,0));     
         fehlerNachrichtLB.setForeground(new Color(100,120,255));          
         pwBT.addActionListener(this);         
         liste.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
         liste.setVisibleRowCount(1);               
         listModel.addElement("verena bit");
         listModel.addElement("verena bit");
         listModel.addElement("verena bit");      
         this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         this.setSize(620,460);
         this.setLocationRelativeTo(null);
         this.setResizable(false);      
         this.setVisible(true);
      }  /*--------------------------------------- Konstruktor -------------------------------------------*/
      public String schulenameSuchen()
        return "";
      public void edvlehrernameEinlesen()
        edvlehrername = System.getProperty("user.name");      
      public void benutzernameEinlesen()
      int index = liste.getSelectedIndex();
           benutzername = (String) liste.getModel().getElementAt(index);       
           benutzername = "CN=" + benutzername + ",OU=Lehrer,OU=ASR";
      public void neuesKennwortEinlesen()
      neuesKennwortTemp = String.valueOf(neuesKennwortPF.getPassword());          
      public void actionPerformed(ActionEvent e)
       char[] neuesKennwortArray = neuesKennwortPF.getPassword();
       char[] neuesKennwortWdhArray = neuesKennwortWdhPF.getPassword();
       if (e.getSource().equals(pwBT))
            if(liste.isSelectionEmpty())
                 JOptionPane.showMessageDialog(frame,"Sie m�ssen einen Benutzer ausw�hlen!");
            return;
       else if(!Arrays.equals(neuesKennwortArray,neuesKennwortWdhArray))
            JOptionPane.showMessageDialog(frame,"Die eingegebenen Kennw�rter sind nicht gleich!");
            return;
       else if(neuesKennwortArray.length == 0 || neuesKennwortWdhArray.length == 0)
            JOptionPane.showMessageDialog(frame,"Es wurde kein Kennwort eingegeben!");
            return;
            benutzernameEinlesen(); // F�r diesen Benutzer wird das Kennwort ge�ndert
            neuesKennwortEinlesen(); // Dieses Kennwort bekommt der obige Benutzer neu
            edvlehrernameEinlesen(); // Anhand dieses EDV-Lehrers wird die Schule ermittelt wo sich der EDV-Lehrer
            // befindet. Dieser schulname bzw. z.B. OU="ASR" wird als Einstieg genommen, wenn sich der EDV-Lehrer
            // mit dem W2K Server befindet. Somit gibt es nur noch das Unterverzeichnis              
            // Eine Hashtable speichert Schl�ssel/Wert Paare
            Hashtable env = new Hashtable();
            String keystore = "C:/Programme/Java/jre1.6.0_01/lib/security/ZertifikatBerlin";
            System.setProperty("javax.net.ssl.trustStore",keystore);
            // Die Methode put der Klasse Hashtable weist die rechten Werte (Stings hier) einen Schl�ssel zu (verschiedene Kontexte hier)
            env.put(Context.INITIAL_CONTEXT_FACTORY,"com.sun.jndi.ldap.LdapCtxFactory");
            env.put(Context.REFERRAL,"follow");
            env.put(Context.PROVIDER_URL,"ldaps://rhein:636");      
            env.put(Context.SECURITY_PROTOCOL,"SSL");
            env.put(Context.SECURITY_AUTHENTICATION, "simple");
           env.put(Context.SECURITY_PRINCIPAL, adminUser);
           env.put(Context.SECURITY_CREDENTIALS,adminPassword);                  
       try
            DirContext ctx = new InitialDirContext(env);
            String base = "dc=bodensee,dc=de";
            String filter = "(sAMAccountName=" + edvlehrername + ")";
            String[] attribut = {"distinguishedName"};
            SearchControls kontroller = new SearchControls();
            kontroller.setSearchScope(SearchControls.SUBTREE_SCOPE);
            kontroller.setReturningAttributes(attribut);
            kontroller.setReturningObjFlag(true);
           NamingEnumeration enm = ctx.search(base,filter,kontroller);
           String DNkette="";
            while(enm.hasMore())
                SearchResult resultat = (SearchResult) enm.next();
                System.out.println(resultat.getNameInNamespace());
                DNkette = resultat.getNameInNamespace();
            // CN=verena bit,OU=Lehrer,OU=ASR ,DC=bodensee,DC=de
            // index=4      ,index=3  ,index=2,index=1    ,incex=0
            LdapName FullDN = new LdapName(DNkette);
             for( int i = 0 ; i < FullDN.size() ; i++ )
                 System.out.println(FullDN.getRdn(i));                                            
             ctx.close();
            // Wert f�r das Kenntwort in der Activev Directory erzeugen
            String neuesKennwort   = "mother"; //neuKennwortPF.getText();
            String neuesKennwortAD = "\"" + neuesKennwort + "\"";
            byte[] newpassword = neuesKennwortAD.getBytes("UTF-16LE");
            // The username to be used for the password change                    
            ModificationItem mods[] = new ModificationItem[1];
            mods[0] = new ModificationItem(DirContext.REPLACE_ATTRIBUTE,new BasicAttribute("unicodePwd", newpassword));
            ctx.modifyAttributes(fehlerNachrichtLB.getText(),mods); */
        catch (Exception er)
            fehlerNachrichtLB.setText(er.toString());
        } // if Ende           
      } // actionPerformed Ende    
          public static void main(String args[]) throws NamingException, UnsupportedEncodingException
             try
                  JFrame.setDefaultLookAndFeelDecorated(true);          
             catch (Exception e)     
               e.printStackTrace();
             MainWindow Fenster = new MainWindow (); 
       } When I run the application the first time enter twice a password and select a user etc.. to fullfill the if clauses and press the button all is working fine: I get this result:
CN=verena bit,OU=Lehrer,OU=ASR,DC=bodensee,DC=de
DC=de
DC=bodensee
OU=ASR
OU=Lehrer
CN=verena bitthe first line with CN=verena bit etc... I get because of this line:
System.out.println(resultat.getNameInNamespace());the next 5 Relative DN`s i get because of this code:
// CN=verena bit,OU=Lehrer,OU=ASR ,DC=bodensee,DC=de
// index=4 ,index=3 ,index=2,index=1 ,incex=0
LdapName FullDN = new LdapName(DNkette);
       for( int i = 0 ; i < FullDN.size() ; i++ )
                 System.out.println(FullDN.getRdn(i));                                            
             }thats all fine, BUT when i hit the button in my application[b] the 2nd time and the above code gets executed my whole app freezes for 7 seconds and i get the error:
javax.naming.ServiceUnavailableException: rhein:636; socket closedand when i click my button the 3rd time the app runs fine again and the fourth time i click my button the app throws me again the error and freezes ??
Can someone help?
another mysterious thing is when i dont use this line of code:
env.put(Context.REFERRAL,"follow");
I get a PartialResultException, but why ?

Answer 1

A really odd thing is also that sometimes the user attribute like "cn" which i do retrieve gets not displayed in my JList when i start the application, but when i close the app and start it again it the JList contains the cn values or not its like a random factor. ???
Someone told me that the garbage collector is not releasing all memory i used in my application so i have to release the resource explicit ??!! is that right? And how do i have to do this? I have never ever read something about that!