How to Avoid 'IllegalStateException' When Populating a JTable from a ResultSet?-javaTutorial-php.cn

How to Avoid 'IllegalStateException' When Populating a JTable from a ResultSet?

Linda Hamilton

Release： 2024-12-21 09:46:10

Original

453 people have browsed it

How to Avoid

How to Populate a JTable from a ResultSet

Problem:

You're experiencing issues populating a JTable from a ResultSet and receiving an "IllegalStateException" error.

Answer:

Using a SwingWorker and try-with-resource Statements:

To simplify the code and utilize advanced features, consider using a SwingWorker and the try-with-resource statement. The SwingWorker allows background tasks to be performed without interfering with the GUI thread. The try-with-resources statement ensures that resources are properly closed.

Here's an example:

import java.sql.*;
import javax.swing.*;
import javax.swing.table.*;

public class GUI extends JFrame {

    // ... (remaining GUI code)

    private void loadData() {
        LOG.info("START loadData method");

        button.setEnabled(false);

        try (Connection conn = DriverManager.getConnection(url, usr, pwd);
             Statement stmt = conn.createStatement()) {

            ResultSet rs = stmt.executeQuery("select * from customer");
            ResultSetMetaData metaData = rs.getMetaData();

            // Names of columns
            Vector<String> columnNames = new Vector<>();
            int columnCount = metaData.getColumnCount();
            for (int i = 1; i <= columnCount; i++) {
                columnNames.add(metaData.getColumnName(i));
            }

            // Data of the table
            Vector<Vector<Object>> data = new Vector<>();
            while (rs.next()) {
                Vector<Object> vector = new Vector<>();
                for (int i = 1; i <= columnCount; i++) {
                    vector.add(rs.getObject(i));
                }
                data.add(vector);
            }

            tableModel.setDataVector(data, columnNames);
        } catch (Exception e) {
            LOG.log(Level.SEVERE, "Exception in Load Data", e);
        }
        button.setEnabled(true);

        LOG.info("END loadData method");
    }

}

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This code utilizes a SwingWorker to perform the data loading in the background. It also leverages the try-with-resources statement to ensure that the connection and statement are properly closed.

Remember to replace url, usr, and pwd with the appropriate values for your database connection.

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