Java : Swing : Hide frame after button pressed

Question

I have a button in a java frame that when pressed it reads a value from a text field and uses that string as a port name attempting to connect to a serial device.

If

Answer 1

Your problem is with this line:

  frame.add(new ConnectionFrame());

You're creating a new ConnectionFrame object, and so the frame that your button tries to close on is not the same as the one being displayed, and this is the source of your problem.

If you change it to,

  //!! frame.add(new ConnectionFrame());
  frame.add(this);

so that the two JFrames are one and the same, things may work more smoothly.

But having said that, your whole design smells bad and I'd rethink it in a more OOP and less static fashion. Also, use dialogs where dialogs are needed, not frames, and rather than dialogs consider swapping views (JPanels) via CardLayout as a better option still.

Myself, I'd create a "dumb" GUI for this, one that creates a JPanel (here in my example it extends a JPanel for simplicity, but I'd avoid extending if not necessary), and I'd let whoever is calling this code decide what to do with the information via some control. For e.g.,

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

@SuppressWarnings("serial")
public class ConnectionPanel extends JPanel {

   private JTextField textField;
   private JButton connectButton;
   private ConnectionPanelControl control;

   public ConnectionPanel(final ConnectionPanelControl control) {
      super(new GridBagLayout());
      this.control = control;

      ActionListener listener = new ActionListener() {
         public void actionPerformed(ActionEvent e) {
            if (control != null) {
               control.connectButtonAction();
            }
         }
      };

      textField = new JTextField(14);
      textField.addActionListener(listener);
      textField.setText("/dev/ttyUSB0");

      connectButton = new JButton("Connect");

      GridBagConstraints c = new GridBagConstraints();
      c.gridwidth = GridBagConstraints.REMAINDER;

      c.fill = GridBagConstraints.HORIZONTAL;
      add(textField, c);

      c.fill = GridBagConstraints.BOTH;
      c.weightx = 1.0;
      c.weighty = 1.0;
      add(connectButton, c);

      connectButton.addActionListener(listener);
   }

   public String getFieldText() {
      return textField.getText();
   }

}

Again, something outside of the simple GUI would make decisions on what to do with the text that the textfield contains and what to do with the GUI that is displaying this JPanel:

public interface ConnectionPanelControl {

   void connectButtonAction();

}

Also, you will likely do any connecting in a background thread so as to not freeze your GUI, probably a SwingWorker. Perhaps something like this:

import java.awt.event.ActionEvent;
import java.util.concurrent.ExecutionException;

import javax.swing.*;

@SuppressWarnings("serial")
public class MyMain extends JPanel {
   public MyMain() {
      add(new JButton(new ConnectionAction("Connect", this)));
   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("My Main");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new MyMain());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

@SuppressWarnings("serial")
class ConnectionAction extends AbstractAction {
   private MyMain myMain;
   private ConnectionPanel cPanel = null;
   private JDialog dialog = null;

   public ConnectionAction(String title, MyMain myMain) {
      super(title);
      this.myMain = myMain;
   }

   @Override
   public void actionPerformed(ActionEvent e) {
      if (dialog == null) {
         dialog = new JDialog(SwingUtilities.getWindowAncestor(myMain));
         dialog.setTitle("Connect");
         dialog.setModal(true);
         cPanel = new ConnectionPanel(new ConnectionPanelControl() {

            @Override
            public void connectButtonAction() {
               final String connectStr = cPanel.getFieldText();
               new MySwingWorker(connectStr).execute();
            }
         });
         dialog.getContentPane().add(cPanel);
         dialog.pack();
         dialog.setLocationRelativeTo(null);
      }
      dialog.setVisible(true);
   }

   private class MySwingWorker extends SwingWorker {
      private String connectStr = "";

      public MySwingWorker(String connectStr) {
         this.connectStr = connectStr;
      }

      @Override
      protected Boolean doInBackground() throws Exception {
         // TODO: make connection and then return a result
         // right now making true if any text in the field
         if (!connectStr.isEmpty()) {
            return true;
         }
         return false;
      }

      @Override
      protected void done() {
         try {
            boolean result = get();
            if (result) {
               System.out.println("connection successful");
               dialog.dispose();
            } else {
               System.out.println("connection not successful");
            }
         } catch (InterruptedException e) {
            e.printStackTrace();
         } catch (ExecutionException e) {
            e.printStackTrace();
         }
      }
   }
}