JTable工作，但JTable子类不会

Question

I have this code that works exactly as desired

package com.grantbroadwater.signInAssistant.view;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;

import org.junit.Test;

import com.grantbroadwater.school.Student;

public class SignInSheetTableTest implements ActionListener{

static SignInSheetTableModel model;
static JTextField tfFirst, tfLast;
static JTable table;

public SignInSheetTableTest() {
    // TODO Auto-generated constructor stub
}

private static JPanel createContentPanel(){
    JPanel panel = new JPanel(new GridLayout(1, 0));

    table = new JTable(new SignInSheetTableModel());
    model = (SignInSheetTableModel)table.getModel();
    table.setPreferredScrollableViewportSize(new Dimension(500, 80));
    table.setFillsViewportHeight(true);

    JScrollPane scrollPane = new JScrollPane(table);

    panel.add(scrollPane);

    return panel;
}

private static void createAndShowGUI(){
    JFrame frame = new JFrame("Table Test");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JPanel panel = SignInSheetTableTest.createContentPanel();
    panel.setOpaque(true);

    JPanel entryPanel = new JPanel(new FlowLayout(FlowLayout.CENTER));
    tfFirst = new JTextField(8);
    tfLast = new JTextField(8);
    JButton btnAdd = new JButton("Add");
    btnAdd.addActionListener(new SignInSheetTableTest());
    JButton btnDelete = new JButton("Delete");
    btnDelete.addActionListener(new ActionListener() {

        @Override
        public void actionPerformed(ActionEvent e) {
            int rowIndex = table.getSelectedRow();
            model.deleteRow(rowIndex);
        }
    });

    entryPanel.add(tfFirst);
    entryPanel.add(tfLast);
    entryPanel.add(btnAdd);
    entryPanel.add(btnDelete);

    JPanel housingPanel = new JPanel(new BorderLayout());
    housingPanel.add(entryPanel, BorderLayout.NORTH);
    housingPanel.add(panel, BorderLayout.CENTER);

    frame.setContentPane(housingPanel);

    frame.pack();
    frame.setVisible(true);
}

public static void main(String[] args) {
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            createAndShowGUI();
        }
    });
}

@Override
public void actionPerformed(ActionEvent e) {
    String first = tfFirst.getText();
    String last = tfLast.getText();

    Student s = new Student(first, last, "11111");

    model.addStudent(s);

    table.scrollRectToVisible(table.getCellRect(table.getRowCount() - 1, 0, true));
}

@Test
public void test(){
    main(null);

    try {
        Thread.sleep(15000);
    } catch (InterruptedException e) {}

}

}

However, when I change The JTable instance to a SignInSheetTable subclass of JTable, and change the constructor to new SignInSheetTable() the program will still execute, but no JTable will appear. I cannot find any solution and I am completly lost as to why a subclass wont work when a super class will the entire SignInSheetTable class is shown below.

package com.grantbroadwater.signInAssistant.view;

import javax.swing.JTable;

import com.grantbroadwater.school.Student;
import com.grantbroadwater.util.Log;
import com.grantbroadwater.util.Log.LogType;

public class SignInSheetTable extends JTable{

private static final long serialVersionUID = 1L;
private SignInSheetTableModel model;

public SignInSheetTable() {
    super(new SignInSheetTableModel());
    model = (SignInSheetTableModel) super.getModel();

    this.setFillsViewportHeight(true);
    new Log(LogType.DEBUG, "new Sign In sheet");
}

public SignInSheetTableModel getModel() {
    return model;
}

public void addStudent(Student student) {
    model.addStudent(student);
}

public void deleteRow(int rowIndex) {
    model.deleteRow(rowIndex);
}

}

Answer 1

Overriding getModel seems to be causing issues with the rest of the program. It's not really required for what you are trying to achieve anyway.

Personally, I'd not bother with the custom table, you're not adding any new functionality to the class, which can't be managed directly through the model, which is where the management should be carried out anyway

I'd also be worried about the over use of static , as this is likely to cause you some issues as the program becomes bigger