title: Connection exception in java jdbc
body: <p>This is one of constructors of class. New object create new record in database. When I create this object "by hand" in source code, everything is fine. But when I put declaration of creation into actionlistener of a button, compiler returns sql exception.</p>
  
  <pre><code>public Pacjent()
      {
          try
          {
              Connection conn = DataBase.Connect();
              Statement stat = conn.createStatement();
              String addRecord = "INSERT INTO records VALUES (12365, 'Bond', 'James', 'M', '12.41.1953r', 'Londyn', 'none');";
              stat.executeUpdate(addRecord);        
      }
      catch(SQLException e)
      {
          e.printStackTrace();
      }    
  
  }
  </code></pre>
  
  <p>Exception that I get is</p>
  
  <blockquote>
    <p>org.postgresql.util.PSQLException: This connection has been closed.
      at
    org.postgresql.jdbc2.AbstractJdbc2Connection.checkClosed(AbstractJdbc2Connection.java:714)
      at
    org.postgresql.jdbc3.AbstractJdbc3Connection.createStatement(AbstractJdbc3Connection.java:230)
      at
    org.postgresql.jdbc2.AbstractJdbc2Connection.createStatement(AbstractJdbc2Connection.java:191)
      at klasySilnika.Pacjent.(Pacjent.java:61)     at
    klasyInterfejsu.NowaKarta$1.actionPerformed(NowaKarta.java:155)   at
    javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
      at
    javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
      at
    javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
      at
    javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
      at
    javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
      at java.awt.Component.processMouseEvent(Component.java:6504)    at
    javax.swing.JComponent.processMouseEvent(JComponent.java:3321)    at
    java.awt.Component.processEvent(Component.java:6269)  at
    java.awt.Container.processEvent(Container.java:2229)  at
    java.awt.Component.dispatchEventImpl(Component.java:4860)     at
    java.awt.Container.dispatchEventImpl(Container.java:2287)     at
    java.awt.Component.dispatchEvent(Component.java:4686)     at
    java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
      at
    java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
      at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
      at java.awt.Container.dispatchEventImpl(Container.java:2273)    at
    java.awt.Window.dispatchEventImpl(Window.java:2713)   at
    java.awt.Component.dispatchEvent(Component.java:4686)     at
    java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)    at
    java.awt.EventQueue.access$000(EventQueue.java:101)   at
    java.awt.EventQueue$3.run(EventQueue.java:666)    at
    java.awt.EventQueue$3.run(EventQueue.java:664)    at
    java.security.AccessController.doPrivileged(Native Method)    at
    java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
      at
    java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
      at java.awt.EventQueue$4.run(EventQueue.java:680)   at
    java.awt.EventQueue$4.run(EventQueue.java:678)    at
    java.security.AccessController.doPrivileged(Native Method)    at
    java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)   at
    java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
      at
    java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
      at
    java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
      at
    java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
      at
    java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)</p>
  </blockquote>
  
  <p>and this is actionlistener:</p>
  
  <pre><code>saveButton.addActionListener
          (
              new ActionListener() 
              {
                  @Override
                  public void actionPerformed(ActionEvent event) 
                  {
                      Pacjent nowy = new Pacjent();
                  }
              }
          );
  </code></pre>
  
  <p>Database.Connect method:</p>
  
  <pre><code>public class DataBase 
  {
      public static Connection Connect()
      {
          return CONNECTION;
      }        
  
      private static Connection CONNECTION = CreateConnection();
  
      private static Connection CreateConnection() 
      {
          try 
          {
              Class.forName("org.postgresql.Driver");
  
              Properties props = new Properties();
              FileInputStream in = new FileInputStream("D:\\projekty\\Arch\\src\\klasySilnika\\bazadanych.properties");
              props.load(in);
              in.close();
  
              String drivers = props.getProperty("jdbc.drivers");
              if(drivers != null) System.setProperty("jdbc.drivers", drivers);
              String url = props.getProperty("jdbc.url");
              String username = props.getProperty("jdbc.username");
              String password = props.getProperty("jdbc.password");
  
              return DriverManager.getConnection(url, username,password);
          }
          catch (ClassNotFoundException e) 
          {
              System.out.println("NO JDBC driver");
          return null;
      }
          catch(IOException e)
          {
              System.out.println("Where is properties file?");
              return null;
          } 
          catch(SQLException e)
          {
              System.out.println("error: adress, user, password?");
              return null;
          }
          finally
          {
             // ...   
          }
      }
  }
  </code></pre>