Question

public Lab7(File file) {
    List<Item> items = null;
    try {
        items = InventoryReader.read(file);
    } catch (ApplicationException e) {
        LOG.error(e.getMessage());
        return;
    }

    EventQueue.invokeLater(new Runnable() {         
        public void run() {
            try {
                for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                    if ("Nimbus".equals(info.getName())) {
                        UIManager.setLookAndFeel(info.getClassName());
                        break;
                    }
                }
            } catch (Exception e) {
                // If Nimbus is not available, use the default.
            }
            try {
                MainFrame frame = new MainFrame(items); // THIS IS WHERE I HAVE TROUBLE
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

Background: I set the constructor of MainFrame to accept a list. How do I do this in the main() of my application?

I get the error:

Cannot refer to a non-final variable “items” inside an inner class defined in a different method

The error is in the MainFrame frame = new MainFrame(items) I can’t seem to pass MainFrame class the items variable… Why is that?

How do I pass this variable into into the MainFrame frame?

Answer 1

You have two choices….

Choice one…

Make the items list final so it is accessiable from within the Runnables context…

public Lab7(File file) {
    final List<Item> items = null; // Make the items final...
    try {
        items = InventoryReader.read(file);
    } catch (ApplicationException e) {
        LOG.error(e.getMessage());
        return;
    }

    EventQueue.invokeLater(new Runnable() {         
        public void run() {
            try {
                for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                    if ("Nimbus".equals(info.getName())) {
                        UIManager.setLookAndFeel(info.getClassName());
                        break;
                    }
                }
            } catch (Exception e) {
                // If Nimbus is not available, use the default.
            }
            try {
                MainFrame frame = new MainFrame(items); // THIS IS WHERE I HAVE TROUBLE
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

Choice two…

Move the items list into the Runnables context

public Lab7(File file) {

    EventQueue.invokeLater(new Runnable() {         
        public void run() {
            // Load the items within the content of the runnable...
            List<Item> items = null;
            try {
                items = InventoryReader.read(file);
            } catch (ApplicationException e) {
                LOG.error(e.getMessage());
                return;
            }
            try {
                for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                    if ("Nimbus".equals(info.getName())) {
                        UIManager.setLookAndFeel(info.getClassName());
                        break;
                    }
                }
            } catch (Exception e) {
                // If Nimbus is not available, use the default.
            }
            try {
                MainFrame frame = new MainFrame(items); // THIS IS WHERE I HAVE TROUBLE
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}