Currently, I have created a Swing GUI to pull data from a basic database.
Eventually, I want to build this into a point of sale system and this is the start.
Once I get the "basics" down I will be able to expand it with different tabs and more items.
For now the query is able to pull the data and I can get the code to print to the console, but when I try to implement it to each label, or text box it will only display on one text box, and not others.
Is a loop needed to cycle through each of my labels, as they are labeled label1, label2...? Then how do I ensure the SQL query loads to each label? In the loop do I sort of the productID?
I tried using multiple queries and get a result set is closed error, and figured there is an easier way to get the data.
Here is the code:
package application;
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.BoxLayout;
import javax.swing.JDesktopPane;
public class Application extends JFrame {
private JTextField prc2;
private JTextField prc1;
//private JTable table;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Application frame = new Application();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public Application() {
getContentPane().setLayout(new BoxLayout(getContentPane(), BoxLayout.X_AXIS));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
JDesktopPane desktopPane = new JDesktopPane();
getContentPane().add(desktopPane);
prc2 = new JTextField();
prc2.setBounds(70, 111, 86, 20);
desktopPane.add(prc2);
prc2.setColumns(10);
prc1 = new JTextField();
prc1.setBounds(70, 80, 86, 20);
desktopPane.add(prc1);
prc1.setColumns(10);
JLabel item1 = new JLabel("New label");
item1.setBounds(10, 83, 46, 14);
desktopPane.add(item1);
JLabel item2 = new JLabel("New label");
item2.setBounds(10, 114, 46, 14);
desktopPane.add(item2);
JLabel qty1 = new JLabel("New label");
qty1.setBounds(181, 83, 46, 14);
desktopPane.add(qty1);
JLabel qty2 = new JLabel("New label");
qty2.setBounds(181, 114, 46, 14);
desktopPane.add(qty2);
JLabel qty = new JLabel("Quantity");
qty.setBounds(181, 40, 46, 14);
desktopPane.add(qty);
JLabel Price = new JLabel("PRICE");
Price.setBounds(70, 40, 46, 14);
desktopPane.add(Price);
Connection conn = null;
//Statement stmt = null;
//ObservableList<String> data = FXCollections.observableArrayList();
try {
String dbURL = "jdbc:sqlserver://localhost:1433;databaseName = Capstone; username=dbuser; password=password";
conn = DriverManager.getConnection(dbURL);
Statement stmt = conn.createStatement();
String sqlStmt = "SELECT * FROM dbo.products WHERE ProductID = 1";
ResultSet rs = stmt.executeQuery(sqlStmt);
while (rs.next()) {
int id = rs.getInt("ProductID");
String productName = rs.getString("productName");
String quant = rs.getString("productQty");
String price = rs.getString("ProductPrice");
item1.setText(productName);
qty1.setText(quant);
prc1.setText(price);
}
String sqlStmt1 = "SELECT * FROM dbo.products WHERE ProductID = 2";
ResultSet rs1 = stmt.executeQuery(sqlStmt1);
while (rs1.next()) {
int id1 = rs.getInt("ProductID");
String productName1 = rs.getString("productName");
String quant1 = rs.getString("productQty");
String price1 = rs.getString("ProductPrice");
item2.setText(productName1);
qty2.setText(quant1);
prc2.setText(price1);
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
If I missed a question that is similar please point me in the right direction.
Related
I have a JCombobox and JTable
and database
jcombobox is filled with the value of first_name of student table from databse.
Whenever I select a name from database I want the value of Course name from course and student_score from score table of the database to be displayed in Jtable.
Basically I want to display the records of selected in JComboBox in Jtable
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import net.proteanit.sql.DbUtils;
import javax.swing.JLabel;
import java.awt.Font;
import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.*;
import java.sql.*;
import javax.swing.event.PopupMenuListener;
import javax.swing.event.PopupMenuEvent;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class ShowScore extends JFrame {
private JPanel contentPane;
private JTable table;
private JComboBox comboBox;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ShowScore frame = new ShowScore();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
Connection con=null;
Score s=new Score();
public ShowScore() {
con=MyConnection.getConnection();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 1238, 761);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel lblScoreSheet = new JLabel("Score Sheet");
lblScoreSheet.setFont(new Font("Times New Roman", Font.BOLD, 28));
lblScoreSheet.setBounds(500, 33, 155, 50);
contentPane.add(lblScoreSheet);
JPanel panel = new JPanel();
panel.setBounds(24, 259, 720, 426);
contentPane.add(panel);
panel.setLayout(null);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setBounds(12, 13, 675, 452);
panel.add(scrollPane);
comboBox = new JComboBox();
comboBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
table = new JTable();
scrollPane.setViewportView(table);
try {
String n=(String)comboBox.getSelectedItem();
String sql="SELECT score.student_id, student.first_name, student.last_name,course.subject, score.student_score FROM ((score INNER JOIN student ON score.student_id=student.id)\r\n" +
" INNER JOIN course ON score.course_id=course.cid WHERE student.first_name=n)";
PreparedStatement ps=con.prepareStatement(sql);
ResultSet rs=ps.executeQuery();
table.setModel(DbUtils.resultSetToTableModel(rs));
JLabel lblName = new JLabel("Name:");
lblName.setFont(new Font("Times New Roman", Font.PLAIN, 18));
lblName.setBounds(102, 107, 56, 16);
contentPane.add(lblName);
} catch (Exception e1) {
e1.printStackTrace();
}
}
});
s.fillScoreCombo(comboBox);
comboBox.setBounds(171, 105, 260, 27);
contentPane.add(comboBox);
table = new JTable();
scrollPane.setViewportView(table);
try {
String n=(String)comboBox.getSelectedItem();
String sql="SELECT score.student_id, student.first_name, student.last_name,course.subject, score.student_score FROM ((score INNER JOIN student ON score.student_id=student.id)\r\n" +
" INNER JOIN course ON score.course_id=course.cid)";
PreparedStatement ps=con.prepareStatement(sql);
ResultSet rs=ps.executeQuery();
table.setModel(DbUtils.resultSetToTableModel(rs));
JLabel lblName = new JLabel("Name:");
lblName.setFont(new Font("Times New Roman", Font.PLAIN, 18));
lblName.setBounds(102, 107, 56, 16);
contentPane.add(lblName);
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
String n=(String)comboBox.getSelectedItem();
String sql="SELECT .... WHERE student.first_name=n)";
That code doesn't do anything with the variable "n". You can't just include "n" as part of the String because all the have is the character "n", not the value of the variable.
You were given a link to a tutorial on using a PreparedStatement in your last question (Populate JTable with the value in JCombobox).
So where do you use the "?" which indicates you want to provide a dynamic value to the SQL statement?
Your basic code should be:
String sql="SELECT ..... where student.first_name = ?)";
PreparedStatement ps = con.prepareStatement(sql);
ps.setString(1, n);
ResultSet rs = ps.executeQuery();
Now the value of the variable "n" will replace the "?" in the SQL string.
Assuming the rest of your SQL is correct then it should work.
I am developing a basic program that has 3 JFrames. A log-in, a registration and a Dashboard to be opened after successful log-in attempt. However, I am getting an error after typing in the username and password and clicking log-in button.
Here's the error:
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ' password='1234'' at line 1
And here's my code:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import com.mysql.jdbc.Statement;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.ImageIcon;
import java.awt.Font;
import javax.swing.JTextField;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.awt.event.ActionEvent;
public class Login extends JFrame {
private JPanel contentPane;
private JTextField txtUsrName;
private JTextField txtPAss;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
Login frame = new Login();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public Login() {
setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
setBounds(100, 100, 450, 348);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JLabel lblLogin = new JLabel("Welcome To TechApp");
lblLogin.setFont(new Font("Tekton Pro", Font.PLAIN, 18));
lblLogin.setBounds(135, 19, 163, 28);
contentPane.add(lblLogin);
JLabel lblUsername = new JLabel("UserName:");
lblUsername.setFont(new Font("Alaska", Font.PLAIN, 15));
lblUsername.setBounds(174, 58, 88, 28);
contentPane.add(lblUsername);
txtUsrName = new JTextField();
txtUsrName.setBounds(145, 90, 132, 20);
contentPane.add(txtUsrName);
txtUsrName.setColumns(10);
JLabel lblPassword = new JLabel("Password:");
lblPassword.setFont(new Font("Alaska", Font.PLAIN, 15));
lblPassword.setBounds(182, 118, 95, 46);
contentPane.add(lblPassword);
txtPAss = new JTextField();
txtPAss.setColumns(10);
txtPAss.setBounds(145, 156, 132, 20);
contentPane.add(txtPAss);
JButton btnNewButton = new JButton("login");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String _username = txtUsrName.getText();
String _password = txtPAss.getText();
String url = "jdbc:mysql://127.0.0.1:3306/javabase";
String user = "java";
String passw = "password";
try{
// 1.Get a connection To Database
Connection myConn = DriverManager.getConnection(url, user, passw);
// 2.Create a statement
Statement myStmt = (Statement) myConn.createStatement();
// 3.Execute SQL Query
String sql = "SELECT userame, password FROM registration WHERE userame='"+_username+"', password='"+_password+"' ";
ResultSet result = myStmt.executeQuery(sql);
//myStmt.executeUpdate(sql);
int count = 0;
while(result.next()){
count = count + 1;
}
if(count == 1){
Dashboard frame = new Dashboard();
frame.setVisible(true);
}
else if(count > 1){
JOptionPane.showMessageDialog(null, "Duplicate User! Access Denied!");
}
else{
JOptionPane.showMessageDialog(null, "User Not Found!");
}
}
catch(Exception ex)
{
ex.printStackTrace();
}
}
});
btnNewButton.setBounds(169, 202, 89, 49);
contentPane.add(btnNewButton);
JButton btnRegister = new JButton("Register");
btnRegister.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Main frame = new Main();
frame.setVisible(true);
}
});
btnRegister.setBounds(168, 264, 89, 23);
contentPane.add(btnRegister);
JLabel lblNewLabel = new JLabel("");
lblNewLabel.setFont(new Font("Alaska", Font.PLAIN, 16));
lblNewLabel.setIcon(new ImageIcon("D:\\ExploitGate\\MAS-9831-Offwhite2.jpg"));
lblNewLabel.setBounds(0, 0, 434, 310);
contentPane.add(lblNewLabel);
}
}
I've searched the stackoverflow forum and carried out the possible solution given here
Can anyone please guide me how to handle this error?
Thanks In Advance :)
All of the above code is basically useless. It's an SQL syntax error, which means it's this one line:
... WHERE userame='"+_username+"', password='"+_password+"' ";
^---
you don't use , to separate where clause arguments. You use boolean operations. and, or, etc...
And note that you're vulnerable to sql injection attacks
You were using a comma , between your WHERE clauses rather than an AND.
String sql = "SELECT userame, password FROM registration WHERE userame='"+_username+"' AND password='"+_password+"' ";
I'm designing a database that can be accessed through a GUI, I have three classes Main, Database and GUI, When I run the main I get an error and the GUI closes followed by a brief error message which I cannot read, not sure where this is going wrong as i believe it can be a number of issues. Thanks for all your help :)
Here is my main class
public class MainApplication {
#SuppressWarnings("unused")
public static void main(String[] args) {
VideoStoreGUI window = new VideoStoreGUI();
}
}
My Database Class:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Scanner;
import javax.swing.JOptionPane;
#SuppressWarnings("unused")
public class DataBase {
static Connection con = null;
static Statement stmt = null;
static ResultSet rs = null;
static Scanner in = new Scanner(System.in);
public void close_connection() {
try
{
con.close();
System.out.println("Database Connections Succesully Closed.");
}
catch (SQLException sqle)
{
System.out.println("Error: failed to close the database");
}
}
public static void addMember(int member_id, String name, String address) // Adding a Member to the Database.
{
try {
String str = "INSERT INTO members (member_id, name, address) values(" + member_id + ", '" + name + "', '"
+ address + "');";
int rows = stmt.executeUpdate(str);
System.out.println("Success in adding member");
} catch (SQLException sqle) {
JOptionPane.showMessageDialog(null, "Error: Could not add member");
}
}
public static void initialize_database() {
try {
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://localhost:3306/videostore";
con = DriverManager.getConnection(url, "root", "admin");
stmt = con.createStatement();
} catch (Exception e) {
System.out.println("Error: Failed to connect to database\n" + e.getMessage());
}
}
public DataBase()
{
initialize_database();
}
}
and my GUI class:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JTabbedPane;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.JMenuBar;
public class VideoStoreGUI extends JFrame {
private JFrame frame;
DataBase my_database;
private JPanel contentPane;
private JTextField textMemberID;
private JTextField textMemberName;
private JTextField textMemberAddress;
/**
* Create the frame.
*/
public VideoStoreGUI() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 400);
JMenuBar menuBar = new JMenuBar();
setJMenuBar(menuBar);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
tabbedPane.setBounds(10, 31, 232, 240);
contentPane.add(tabbedPane);
JPanel panel = new JPanel();
tabbedPane.addTab("Members", null, panel, null);
panel.setLayout(null);
JLabel labelMemberID = new JLabel("Members ID");
labelMemberID.setBounds(10, 11, 85, 14);
panel.add(labelMemberID);
JLabel labelMemberName = new JLabel("Members Name");
labelMemberName.setBounds(10, 36, 85, 14);
panel.add(labelMemberName);
JLabel labelMemberAddress = new JLabel("Members Address");
labelMemberAddress.setBounds(10, 61, 85, 14);
panel.add(labelMemberAddress);
textMemberID = new JTextField();
textMemberID.setBounds(131, 8, 86, 20);
panel.add(textMemberID);
textMemberID.setColumns(10);
textMemberName = new JTextField();
textMemberName.setColumns(10);
textMemberName.setBounds(131, 33, 86, 20);
panel.add(textMemberName);
textMemberAddress = new JTextField();
textMemberAddress.setColumns(10);
textMemberAddress.setBounds(131, 58, 86, 20);
panel.add(textMemberAddress);
JButton buttonAddMember = new JButton("Add Member");
buttonAddMember.setBounds(10, 86, 102, 23);
panel.add(buttonAddMember);
JButton buttonRemoveMember = new JButton("Add Member");
buttonRemoveMember.setBounds(115, 86, 102, 23);
panel.add(buttonRemoveMember);
JButton buttonSearchMember = new JButton("Add Member");
buttonSearchMember.setBounds(66, 120, 102, 23);
panel.add(buttonSearchMember);
JPanel panel_1 = new JPanel();
tabbedPane.addTab("Products", null, panel_1, null);
}
}
I see only one place where you can get popup. You can keep it if you like but add system output and be sure about your message:
catch (SQLException sqle) {
System.out.writeln("Exception:"+sqle);
JOptionPane.showMessageDialog(null, "Error: Could not add member");
}
Based on place of this message I think you have wrong sql or database. I would suggest that you print your sql and results of it too.
The main reason this was not working for me was because I had removed setVisable(true) from the GUI and forgot to add it back to the method, I was then receiving an Error "AWT-EventQueue-0" this was to do with the way my database connection was set up, removing and adding the JDBC driver again resolved this.
I have a textbox which sent something to database and jtable list the values from database. But when i add something to database. Jtable dont show it in same time. when i close the program and debug again, it shows that time. I want Jtabel to show textbox value when i click the save button. How can i create a dynamic jtable?
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Vector;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableColumn;
public class Topic extends JFrame {
private static final long serialVersionUID = 1L;
JFrame frmTopic;
JPanel pnl, pnl_generaltopic;
static JTextField txt_topic;
JLabel lbl_topicNme, lbl_topicpage;
JButton btn_close, btn_update, btn_save;
public static Connection con = null;
public static ResultSet rs = null;
public static Statement st = null;
static Vector<Vector<String>> data = new Vector<Vector<String>>();
private JScrollPane scrollPane;
private static JTable table;
public Topic() {
pnl_generaltopic = new JPanel();
pnl_generaltopic.setBackground(Color.lightGray);
pnl_generaltopic.setLayout(null);
frmTopic = new JFrame("Topic");
frmTopic.addWindowListener(new WindowAdapter() {
#Override
public void windowOpened(WindowEvent arg0) {
con = Dbconnect.conect();
}
});
frmTopic.setTitle("E-TEST");
frmTopic.setBounds(100, 100, 500, 500);
frmTopic.setVisible(true);
frmTopic.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frmTopic.getContentPane().setLayout(new BorderLayout(0, 0));
frmTopic.getContentPane().add(pnl_generaltopic);
topicPanel();
topicTable();
}
public void topicPanel() {
JPanel panel_addingNewTopic = new JPanel();
panel_addingNewTopic.setBounds(10, 0, 464, 203);
pnl_generaltopic.add(panel_addingNewTopic);
panel_addingNewTopic.setLayout(null);
btn_save = new JButton("Save");
btn_save.setBounds(65, 166, 67, 23);
panel_addingNewTopic.add(btn_save);
btn_update = new JButton("Update");
btn_update.setBounds(142, 162, 90, 30);
panel_addingNewTopic.add(btn_update);
btn_close = new JButton("Close");
btn_close.setBounds(240, 162, 90, 30);
panel_addingNewTopic.add(btn_close);
txt_topic = new JTextField();
txt_topic.setBounds(65, 59, 270, 71);
panel_addingNewTopic.add(txt_topic);
lbl_topicNme = new JLabel("Topic Name");
lbl_topicNme.setBounds(10, 65, 150, 59);
panel_addingNewTopic.add(lbl_topicNme);
lbl_topicpage = new JLabel("Topic Page");
lbl_topicpage.setBounds(10, 11, 300, 20);
panel_addingNewTopic.add(lbl_topicpage);
lbl_topicpage.setFont(new Font("arial", Font.BOLD, 15));
btn_close.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frmTopic.dispose();
}
}
);
btn_save.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
try {
st = con.createStatement();
String sorgu = "insert into topic " + "(topicname)"
+ "VALUES ('" + txt_topic.getText() + "')";
st.executeUpdate(sorgu);
JOptionPane.showMessageDialog(Topic.this, "Topic was added");
} catch (Exception s) {
System.out.print(s.getMessage());
}
}
}
);
}
public void topicTable() {
scrollPane = new JScrollPane();
scrollPane.setBounds(10, 226, 464, 190);
pnl_generaltopic.add(scrollPane);
Vector<String> headers = new Vector<String>();
headers.add("Topic Name");
getData();
//this is the model which contain actual body of JTable
DefaultTableModel model = new DefaultTableModel(data, headers);
table = new JTable(model);
scrollPane.setColumnHeaderView(table);
table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
//table=new JTable(model);
//table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
header_size();
//JScrollPane scroll = new JScrollPane(table);
scrollPane.setHorizontalScrollBarPolicy(
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scrollPane.setVerticalScrollBarPolicy(
JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
pack();
setResizable(false);
setVisible(true);
}
/**
* Setting the particular Column Size in JTable
*/
public static void header_size() {
TableColumn column = table.getColumnModel().getColumn(0);
column.setPreferredWidth(100);
column = table.getColumnModel().getColumn(0);
column.setPreferredWidth(350);
}
/**
* Fetching Data From MySql Database
* and storing in a Vector of a Vector
* to Display in JTable
*/
private static void getData() {
// Enter Your MySQL Database Table name in below Select Query.
String str = "select * from topics";
Connection con;
ResultSet rs;
Statement st;
try {
con = DriverManager.getConnection("jdbc:mysql://" + "localhost:3306/database", "root", "1234");
st = con.createStatement();
rs = st.executeQuery(str);
while (rs.next()) {
Vector<String> d = new Vector<String>();
d.add(rs.getString("topicname"));
d.add("\n\n\n\n\n\n\n");
data.add(d);
}
} catch (SQLException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
Topic topic = new Topic();
topic.setVisible(false);
}
}
You can use the addRow(...) method of the DefaultTableModel to dynamically add a row of data in the model.
So if the update to your database is successful, then you would invoke the addRow() method.
Also, you should use a PreparedStatement when using SQL. It will make creating the SQL easier since you don't need to worry about the delimiters. Simple example to give you an idea:
String sql = "INSERT INTO Page (Name, Title) VALUES (?, ?)";
PreparedStatement stmt = connection.prepareStatement(sql);
stmt.setString( 1, "Name1" );
stmt.setString( 2, textField.getText() );
stmt.executeUpdate();
I have a query. I have a database, and I am trying to write code, so that a record in the database can be created from the java software.
I have a connector class that connects to the database, then a registerStudent class, that lets the user type in value into 2 textfields. then the values should be used to create a record in the database table.
when i hit the submit button it gives me this error code:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at RegisterStudent$2.actionPerformed(RegisterStudent.java:99)
FYI - Line 99 Code =
con.stmt.executeUpdate("INSERT INTO staff (Name, Profession)"+"VALUES"+"("+"'"+name+"',"+"'"+profession+"')");
This is my code for the registerStudent class:
import java.awt.Component;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.Border;
import javax.swing.border.LineBorder;
import javax.swing.JLabel;
import java.awt.Font;
import javax.swing.JTextField;
import javax.swing.JButton;
import javax.swing.JOptionPane;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.sql.SQLException;
public class RegisterStudent
{
public RegisterStudent() {
initialize();
}
public JFrame frmRegisterStudent;
Connector con;
private JTextField textField_1;
private JTextField textField_2;
// initialise the frame
private void initialize() {
frmRegisterStudent = new JFrame();
frmRegisterStudent.setTitle("LEC AdminPro: RegisterStudents");
frmRegisterStudent.setBounds(100, 100, 413, 225);
frmRegisterStudent.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
frmRegisterStudent.setLocationRelativeTo(null);
Border border = LineBorder.createGrayLineBorder();
frmRegisterStudent.getContentPane().setLayout(null);
con = new Connector();
JPanel panel_1 = new JPanel();
panel_1.setBounds(0, 0, 397, 189);
frmRegisterStudent.getContentPane().add(panel_1);
panel_1.setBorder(border);
panel_1.setLayout(null);
JLabel lblRegister = new JLabel("Register Student");
lblRegister.setFont(new Font("Tahoma", Font.BOLD, 12));
lblRegister.setBounds(10, 11, 124, 20);
panel_1.add(lblRegister);
JLabel lblSurname = new JLabel("Name");
lblSurname.setFont(new Font("Arial", Font.PLAIN, 11));
lblSurname.setBounds(10, 63, 69, 14);
panel_1.add(lblSurname);
JLabel lblDob = new JLabel("Profession");
lblDob.setFont(new Font("Arial", Font.PLAIN, 11));
lblDob.setBounds(10, 88, 69, 14);
panel_1.add(lblDob);
textField_1 = new JTextField();
textField_1.setColumns(10);
textField_1.setBounds(104, 63, 266, 20);
panel_1.add(textField_1);
textField_2 = new JTextField();
textField_2.setColumns(10);
textField_2.setBounds(104, 88, 266, 20);
panel_1.add(textField_2);
JButton btnNewButton = new JButton("Cancel");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
Object[] options = {"Yes", "No"};
Component form = null;
int n = JOptionPane.showOptionDialog(form, "Would you like to cancel the new Registration?", "Exit Confirmation", JOptionPane.YES_NO_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE, null, options, options);
if(n == JOptionPane.YES_OPTION) {
frmRegisterStudent.setVisible(false);
}
}
});
btnNewButton.setBounds(280, 119, 89, 23);
panel_1.add(btnNewButton);
JButton button = new JButton("Submit");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
String name = textField_1.getText();
String profession = textField_1.getText();
try {
con.stmt.executeUpdate("INSERT INTO staff (Name, Profession)"+"VALUES"+"("+"'"+name+"',"+"'"+profession+"')");
JOptionPane.showMessageDialog(frmRegisterStudent, "New Record has been added");
} catch (SQLException e) {
System.out.println("Record couldn't be added!");
e.printStackTrace();
}
}
});
button.setBounds(181, 119, 89, 23);
panel_1.add(button);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
RegisterStudent window = new RegisterStudent();
window.frmRegisterStudent.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
public void setVisible(boolean b) {
frmRegisterStudent.setVisible(true);
}
}
It looks like the problem is in the Connector class, which has a stmt field that does not get initialized.
Use this instead of the line with the NullPointerException
con.stmt = con.conn.prepareStatement("insert into staff (name, profession) values (?, ?)");
con.stmt.setString(1, name);
con.stmt.setString(2, profession);
con.stmt.executeUpdate();
But note that this is pretty bad design.
Is your connector null? I see the stmt is a field in the connector, have you initialized it?
By the way using a prepared statement is much better in your case, because it will escape the Strings (for example if they have "'" in them).
PreparedStatement pstmt = connection.prepareStatement("insert into staff (name, profession) values (?, ?)");
pstmt.setString(1, name);
pstmt.setString(2, profession);
pstmt.executeUpdate();