swing - Java: GUI - JButton opening new JPanel and reading the JTextFields

Question

My problem is making my Main class and Journal class connect together, in the Main class users will input two variables and click the button to create the table, in the Journal class it will read the two variables.

I used netbeans to create the Main class and my own methods to create the table class please help! Thanks! This is the part of the Main class Netbeans tells me to edit when I right click > Events > Action > Action Performed

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
}                                        

and my Journal class, I tried making it read JTextField 1 and 2 but I do not know how to combine them.

import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;
public class Journal extends JPanel
{
    public Journal() 
    {

        String colN1 = "Date";
        String colN2 = "Student"; 
        int a = Integer.parseInt(newJournal.jTextField1.getText());
        int b = Integer.parseInt(newJournal.jTextField2.getText());
        int c = a*2/b;
        int col = c*2;
        String[] columnNames = new String[col];
        for(int colF = 0; colF < col; colF++)
        {
            if(colF%2 == 0)
            {
                columnNames[colF] = colN1;
            }
            else
            {
                columnNames[colF] = colN2;
            }
        }
        int row = b;
        int d = 1;
        int s = 1;
        int x = 0;
        Integer f = new Integer(1);
        Object[][] data = new Object[row][col];
        for (int col1 = 0; col1 < data[0].length; col1++)
        {
            for (int row1 = 0; row1<data.length; row1++)
            {

                if(d > b)
                {
                    d = 1;
                }
                else if(s > a || x > 2)
                {
                    s = 1;
                    x++;
                }
                else if (row1 > row)
                {
                    row1 = 0;
                }
                else if(col1%2 == 0)
                {
                    data[row1][col1]= "Day " + d;
                    d++;  
                }
                else
                {
                    data[row1][col1]= s;
                    s++;
                }
            }
        }
        for (int col2 = 0; col2 < data[0].length; col2++)
        {
            for (int row2 = 0; row2<data.length; row2++)
            {
                if(s > a || x > 2)
                {
                    s = 1;
                    x++;
                }
                else if(s!=data[row2][col2]&&col2%2!=0)
                {
                    data[row2][col2] = s;
                    s++;
                }
            }
        }
        for (int row3 = 0; row3<data.length; row3++)
        {
            for (int col3 = 0; col3 < data[0].length; col3++)
            {
                int rowA = row3 + 1;
                int rowS = row3 - 1;
                int rows = 1;
                int colA = col3 + 1;
                int colS = col3 - 1;
                int cols = 1;
                if(s > a || x > 2)
                {
                    s = 1;
                    x++;
                }
                else if(s==data[rowA][cols] && s == data[rowS][cols])
                {
                    cols=cols+2;
                }
                else if (s == data[rows][colA] && s == data [rows][colS])
                {
                    rows++;
                }
                else if(s!=data[row3][col3]&&col3%2!=0)
                {
                    data[row3][col3] = s;
                    s++;
                }
            }
        }

        JTable table = new JTable(data, columnNames);

        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        JScrollPane scrollPane = new JScrollPane(table);
        add(scrollPane);
    }

    private static void gui()
    {
        JFrame gui = new JFrame();
        gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        gui.setTitle("Journal List");
        gui.setSize(700,200);
        gui.setLocationRelativeTo(null);
        gui.setVisible(true);
        gui.add(new Journal());
    }

    public static void main(String[] args)
    {

        EventQueue.invokeLater(new Runnable()
            {
                public void run()
                {
                    gui();
                }
            });
    }
}

Answer 1

Currently your JTable is locally scoped in the Journal constructor, so it can't be accessed from anywhere else. What you want to do is declare it as a class-member and have a getter for it.

  public class Journal extends JPanel {
      private JTable table;

      public Journal() {
          table = new JTable(...);
      }

      public JTable getTable() {
          return table;
      }
  }

Now the table can be accessed and retrieved from the Main class using the getTable().

Also you'll want to use a TableModel to update data dynamically. Yo can use a simple, already implemented DefaultTableModel. You want to set this model to the JTable. Something like this

 public Journal() {
     ...
     DefaultTableModel model = new DefaultTableModel(data, columns);
     table = new JTable(model);
 }

So you have everything set in for your Main class. In your actionPerfomed you can do something like this

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    String data1 = textField1.getText();
    String data2 = textField2.getText();

    JTable table = journal.getTable();
    DefaultTableMode model = (DefaultTableModel)table.getModel();

    model.addRow( new Object[] { data1, data2 } );
}  

---

Side Notes

• You don't need two main methods, as I assume the Main class already has a main method.
• Also take a look at The Use of Multiple JFrames, Good/Bad Practice?. It looks like your Journal class use a JFrame in its main method, and I assume your Main class is a JFrame also. What you can do is just make Journal a JDialog and add the JTable to it.