将一个JPanel设置为另一个类中的新JPanel

Question

I have a main Java GUI which looks like this .

Basically there is a containerPanel which contains a cardPanel of cards (the right hand side), and then a GridLayout tabPanel on the left hand side.

The cardPanel contains many cards, one of which is a patientCard. This basically shows a JPanel which contains a JTable of patients.

I want to call code like:

cards = new CardLayout(); 
cardPanel = new JPanel();
containerPanel.add(cardPanel, BorderLayout.CENTER);
cardPanel.setLayout(cards); 
cards.show(cardPanel, null);

patientsCard = new CSVTable();
cardPanel.add(patientsCard, "View Patients Panel");

And then call it to view via:

viewButton = new JButton("View Patients"); 
        tabsPanel.add(viewButton);
        viewButton.addActionListener(new ActionListener() { 
            @Override public void actionPerformed(ActionEvent event) {
                cards.show(cardPanel,"View Patients Panel");
            } 
        });

Not that this code actually works for my registration panel which is not called from another class, but just like:

registrationCard = new JPanel()

For some reason, this CSVTable panel when called from within the main GUI is not displaying at all, even if I do simple things like change the background. I have tried various steps including trying to include a new Runnable in CSVTable in the try method, changing the type of patientCard to type CSVTable object, changing the variables to public , putting the CSVTable() code in a public static void main(String[] args) method rather than a constructor.

However, I know the CSVTable code works, because I tried creating a new swing application window via the windowbuilder with exactly the same code (but just with a JFrame included, not just a JPanel), and it runs and looks like this .

For info, here is my CSVTable() class code:

package hospitalsystem;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.io.FileReader;
import java.io.Reader;
import java.util.Arrays;
import java.util.Scanner;
import java.util.Vector;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextPane;
import javax.swing.table.DefaultTableModel;


public class CSVTable extends JPanel {

    /*
     * These are all static because I initially had these being referred to in a main class in CSVTable
     */
    public static String datafile;
    public static DefaultTableModel m;
    public static JPanel viewCard;
    public static FileReader fin;
    public static JScrollPane patientScrollPane;
    public static JTable patientTable; 
    public static Dimension patientPaneDimension;


     public DefaultTableModel createTableModel(Reader in, Vector<Object> headers) {
            DefaultTableModel model = null;
            Scanner s = null;
            Vector<Object> c;
            try {
                Vector<Vector<Object>> rows = new Vector<Vector<Object>>();
                s = new Scanner(in);
                while (s.hasNextLine()) {
                    rows.add(new Vector<Object>(
                            Arrays.asList(s.nextLine().split("\\s*,\\s*", -1))));
                }
                if (headers == null) {
                    headers = rows.remove(0);
                    model = new DefaultTableModel(rows, headers);
                } else {
                    model = new DefaultTableModel(rows, headers);
                }
                return model;
            } finally {
                s.close();
            }
        }


    public CSVTable(){
        try {    
            datafile = "[my file location, kept private]";
            fin = new FileReader(datafile);
            m = createTableModel(fin, null);//This uses the method above
            System.out.println(m);
            viewCard = new JPanel();
            viewCard.setLayout(new BorderLayout());
            viewCard.setBackground(Color.BLACK);//This was not being called at all
            patientTable = new JTable(m);
            patientTable.setPreferredScrollableViewportSize(new Dimension(700, 70));
            patientTable.setFillsViewportHeight(true);
            patientScrollPane = new JScrollPane(patientTable);
            patientScrollPane.setBackground(Color.WHITE);
            patientScrollPane.setOpaque(true);
            patientTable.setBackground(Color.WHITE);
            viewCard.add(patientScrollPane, BorderLayout.CENTER);
            viewCard.add(patientTable, BorderLayout.CENTER);
            viewCard.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

Answer 1

I have worked this out myself.

I was calling

patientsCard = new CSVTable();

Which should generate a new JPanel automatically. However, within the CSVTable class, I also generated a new JPanel via:

viewCard = new JPanel();

When I remove all references to viewCard , this new JPanel, in the CSVTable class, my panel correctly renders in the main GUI.

Hope this helps others in the same situation.