Java Project Tutorial - How to Create a Custom Table and Scrollbars Using Graphics In Java NetBeans 

import javax.swing.*; import javax.swing.table.DefaultTableModel; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.HashSet; public class UniqueEntryJTableDemo extends JFrame { private JTable table; private DefaultTableModel model; private JTextField textField; private HashSet uniqueEntries; public UniqueEntryJTableDemo() { setTitle("Unique Entry JTable"); setDefaultCloseOperation(EXIT_ON_CLOSE); setSize(400, 300); // Initialize HashSet to store unique entries uniqueEntries = new HashSet(); // Create table model model = new DefaultTableModel(); model.addColumn("Name"); // Create JTable with the model table = new JTable(model); // Create JTextField for input textField = new JTextField(20); // Create JButton to add entry JButton addButton = new JButton("Add"); addButton.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { addEntry(); } }); // Create JPanel for input components JPanel inputPanel = new JPanel(); inputPanel.add(textField); inputPanel.add(addButton); // Add components to JFrame add(new JScrollPane(table), BorderLayout.CENTER); add(inputPanel, BorderLayout.SOUTH); } private void addEntry() { String entry = textField.getText().trim(); if (!entry.isEmpty() && !uniqueEntries.contains(entry)) { uniqueEntries.add(entry); // Add to HashSet model.addRow(new Object[]{entry}); // Add to JTable textField.setText(""); // Clear text field } else { JOptionPane.showMessageDialog(this, "Duplicate entry or empty string!", "Error", JOptionPane.ERROR_MESSAGE); } } public static void main(String[] args) { new UniqueEntryJTableDemo().setVisible(true); } }