CODEWITHSUNDEEP
javaswingfile-iojframe
fantom
fantom

Reputation: 864

How do I check if a file is saved when the user tries to close the window button?

I have a couple of classes but I am only posting this Main class I have. Most of this code was taken from my professor's sample program. My problem is I want to run a check ONCE the window button is closed. The 'check' is going to see if a Boolean variable 'saved' from another class is True or False, and act accordingly. THEN, close the window. So far I have this, but I am getting an error from the JFrameL. How do I use the WindowClosing method from another class? I see that I am not supposed to call it on its own?

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;


public class Main {

public static JFrameL frame;

public static void main(String[] args) {
    // Create a window.
    frame  = new JFrameL("Checking Account Actions");

    // Set the size of the window.
    frame.setSize(450, 350);
    frame.setAlwaysOnTop(true);

    // Specify what happens when the close button is clicked.
    frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);

    CheckingAccountActions panel = new CheckingAccountActions();
    frame.getContentPane().add(panel);
    frame.pack();

    // Display the window
    frame.setVisible(true);

}

public class JFrameL extends JFrame {

    public JFrameL(String title) {
        super(title);
        FrameListener listener = new FrameListener();
        addWindowListener(listener);
    }

    private class FrameListener extends WindowAdapter {

        public void windowClosing(WindowEvent e) {
            System.out.println("WindowListener method called: windowClosed.");
            if(!CheckingAccountActions.saved) {
                String  message = "The data in the application is not saved.\n"
                                + "Would you like to save it before exiting the application?";
                int confirm = JOptionPane.showConfirmDialog (null, message);

                if (confirm == JOptionPane.YES_OPTION)
                    CheckingAccountActions.chooseFile(2);
            }
            Main.frame.setVisible(false);
            System.exit(0);
        }
    }
}

 }

Error message I am receiving on line 2 from main():

"No enclosing instance of type Main is accessible. Must qualify the allocation with an enclosing instance of type Main (e.g. x.new A() where x is an instance of Main)."

Upvotes: 1

Views: 1224

Answers (2)

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285403

  1. You appear to be trying to call instance methods in a static way. Don't do this.
  2. I wouldn't extend JFrame for what you are trying to do.
  3. I'd create my own WindowListener class, one that has a valid reference to the object that knows whether or not a file save is needed and whether it has been done.

e.g.,

class MyWindowAdapter extends WindowAdapter {
  private CheckingAccountActions checkActions;

  public MyWindowAdapter(CheckingAccountActions checkActions) {
    this.checkActions = checkActions;
  }

  // in your window closing method
  // check the state of checkActions first before doing anything
    public void windowClosing(WindowEvent e) {
        // note -- don't check for saved in a static way
        // use a method on the instance.
        if(!checkActions.getSaved()) {
            // etc...
        }

        JFrame frame = (JFrame)e.getSource();
        frame.setVisible(false);

        // Main.frame.setVisible(false);
        System.exit(0);
    }
}

Then in main:

public static void main(String[] args) {
    frame  = new JFrame("Checking Account Actions");
    frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);

    CheckingAccountActions panel = new CheckingAccountActions();

    MyWindowAdapter winAdapter = new MyWindowAdapter(panel);
    frame.addWindowListener(winAdapter);

    frame.getContentPane().add(panel);
    frame.pack();

    frame.setVisible(true);
}

Edit

This smells of static over-use: CheckingAccountActions.saved.

Upvotes: 3

j__m
j__m

Reputation: 9625

I suspect what you need to do is move panel so you can access it later.

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;


public class Main {

public static JFrameL frame;
public static CheckingAccountActions panel;

public static void main(String[] args) {
    // Create a window.
    frame  = new JFrameL("Checking Account Actions");

    // Set the size of the window.
    frame.setSize(450, 350);
    frame.setAlwaysOnTop(true);

    // Specify what happens when the close button is clicked.
    frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);

    panel = new CheckingAccountActions();
    frame.getContentPane().add(panel);
    frame.pack();

    // Display the window
    frame.setVisible(true);

}

public class JFrameL extends JFrame {

    public JFrameL(String title) {
        super(title);
        FrameListener listener = new FrameListener();
        addWindowListener(listener);
    }

    private class FrameListener extends WindowAdapter {

        public void windowClosing(WindowEvent e) {
            System.out.println("WindowListener method called: windowClosed.");
            if(!panel.saved) {
                String  message = "The data in the application is not saved.\n"
                                + "Would you like to save it before exiting the application?";
                int confirm = JOptionPane.showConfirmDialog (null, message);

                if (confirm == JOptionPane.YES_OPTION)
                    panel.chooseFile(2);
            }
            Main.frame.setVisible(false);
            System.exit(0);
        }
    }
}

Upvotes: 0

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