I am trying to delete a row from my database and I am getting the following error
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
Also I have "where ID = 1"
Is it possible for me to have a getmethod to get the key(number) instead of having to type 1, 2 or 3 etc. a copy of the code is below
package prototype4;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JTextField;
import java.awt.TextArea;
import java.awt.event.ActionEvent;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.DefaultTableModel;
import java.sql.*;
import java.util.logging.Level;
import java.util.logging.Logger;
public class DeleteSong extends JFrame implements ActionListener {
private Connection con;
private Statement stmt;
private ResultSet res;
JTextField songNo = new JTextField(7);
TextArea information = new TextArea(2, 50);
JButton delete = new JButton("Delete Song");
JButton update = new JButton("Update Table");
static String[] columnNames = {"trackNo", "Artist", "trackName"};
static Object[][] data = null;
static JTable table;
static DefaultTableModel modeltable = new DefaultTableModel(data, columnNames);
Font timeFont = new Font("Gill Sans MT", Font.BOLD, 15);
//object constructor which delcares the physical look of the frame including the title
public DeleteSong() {
setLayout(new BorderLayout());
setBounds(100, 100, 1000, 250); //set the size of the frame in pixels
setTitle("Delete Song"); //set the title of the frame
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel top = new JPanel();
top.add(new JLabel("Enter Song Number:"));
top.add(songNo);
top.add(delete);
delete.addActionListener(this);
top.add(update);
update.addActionListener(this);
add("North", top);
JPanel middle = new JPanel(); line
middle.add(information);
add("Center", middle);
JPanel panel2 = new JPanel();
table = new JTable(modeltable);
table.setPreferredScrollableViewportSize(new Dimension(500, 70));
table.setFillsViewportHeight(true);
JScrollPane scrollPane = new JScrollPane(table);
panel2.add(scrollPane);
add("West", panel2);
setResizable(false);
setVisible(true);
setLocationRelativeTo(null);
information.setFont(timeFont);
information.setForeground(Color.BLUE);
}
public void actionPerformed(ActionEvent e) {
try {
stmt = con.createStatement();
res = stmt.executeQuery("SELECT * FROM LibraryTable");
String key = songNo.getText(); //get the song number from the songNo text field
String name = LibraryData.getName(key); //get the name of the song from the LibraryData.java(another java class)
//conditions
if (name == null) {
information.setText("No such song");
} else {
int confirm = JOptionPane.showConfirmDialog(null, "Are you sure you want to delete " + key + " " + name.toUpperCase() + " ?");
if (confirm == 0) {
LibraryData.remove(key);
stmt = con.createStatement();
String sql = "DELETE FROM LibraryTable "
+ "WHERE ID = 1";
stmt.executeUpdate(sql);
information.setText(key + "-" + name + " has been deleted and database updated!");
}
}
} catch (SQLException ex) {
Logger.getLogger(DeleteSong.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at prototype4.DeleteSong.actionPerformed(DeleteSong.java:92) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252) at java.awt.Component.processMouseEvent(Component.java:6505) at javax.swing.JComponent.processMouseEvent(JComponent.java:3321) at java.awt.Component.processEvent(Component.java:6270) at java.awt.Container.processEvent(Container.java:2229) at java.awt.Component.dispatchEventImpl(Component.java:4861) at java.awt.Container.dispatchEventImpl(Container.java:2287) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422) at java.awt.Container.dispatchEventImpl(Container.java:2273) at java.awt.Window.dispatchEventImpl(Window.java:2719) at java.awt.Component.dispatchEvent(Component.java:4687) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735) at java.awt.EventQueue.access$200(EventQueue.java:103) at java.awt.EventQueue$3.run(EventQueue.java:694) at java.awt.EventQueue$3.run(EventQueue.java:692) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87) at java.awt.EventQueue$4.run(EventQueue.java:708) at java.awt.EventQueue$4.run(EventQueue.java:706) at java.security.AccessController.doPrivileged(Native Method) at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76) at java.awt.EventQueue.dispatchEvent(EventQueue.java:705) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138) at java.awt.EventDispatchThread.run(EventDispatchThread.java:91) Picked up JAVA_TOOL_OPTIONS: -Djava.vendor="New Oracle"
