I was trying to develop a stockManager application in java swing with MySQL .While

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Asked: June 4, 20262026-06-04T04:32:36+00:00 2026-06-04T04:32:36+00:00

I was trying to develop a stockManager application in java swing with MySQL .While

0

I was trying to develop a stockManager application in java swing with MySQL .While running the code i was getting the following error:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at org.bil.service.StockManager.addNewItem(StockManager.java:355)
at org.bil.service.StockManager.actionPerformed(StockManager.java:163)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)

I am attaching the code below..Its little long….Kindly pardon..

StockManager.java

package org.bil.service;

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

import org.res.bil.PersonInfo;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.*;

public class StockManager implements ActionListener {

ArrayList itemList;
StockManagerDAO stockManagerDAO;
// Declaration
JPanel topPanel, bottomPanel;
JScrollPane scrollPane;
JFrame frame;
JMenuBar menubar = new JMenuBar();;
JMenu menu = new JMenu();
JMenuItem menuItem;
Toolkit kit = Toolkit.getDefaultToolkit();
Dimension screenSize = kit.getScreenSize();
int screenHeight = screenSize.height;
int screenWidth = screenSize.width;
Image img = kit.getImage("images/icon.JPG");
String entryDate;
int itemNo;
String itemName;
double unitPrice;
double qty;
double totalPrice;
String supplier;
String remarks;
JTextField txtEntryDate;
JTextField txtItemNo;
JTextField txtItemName;
JTextField txtUnitPrice;
JTextField txtQty;
JTextField txtTotalPrice;
JTextField txtSupplier;
JTextField txtRemarks;
JButton BttnSaveAdded;
// Main
public static void main(String[] args) {

    new StockManager();
}

// Constructor
StockManager() {

    frame = new JFrame("Stock Manager");
    frame.setSize(680, 200);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLocation(screenWidth / 4, screenHeight / 4);
    frame.setIconImage(img);
    frame.show();
    userInterface();
    itemList = new ArrayList();
    stockManagerDAO = new StockManagerDAO();
}

// User Interface
public void userInterface()

{
    menubar.add(menu);
    menu = new JMenu("Options");
    menuItem = new JMenuItem("Add New Item");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menuItem = new JMenuItem("Delete Item");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menuItem = new JMenuItem("Search Item");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menuItem = new JMenuItem("Sort Item");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menuItem = new JMenuItem("View All Item");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menuItem = new JMenuItem("Backup Item");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menubar.add(menu);
    menu = new JMenu("Help");
    menuItem = new JMenuItem("Help Contents");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menuItem = new JMenuItem("About");
    menu.add(menuItem);
    menuItem.addActionListener(this);
    menubar.add(menu);
    frame.setJMenuBar(menubar);
    JPanel topPanel = new JPanel();
    JPanel bottomPanel = new JPanel();
    // Add Buttons To Bottom Panel
    JButton addItem = new JButton("Add New Item");
    JButton deleteItem = new JButton("Delete Item");
    JButton searchItem = new JButton("Item");
    JButton sortItem = new JButton("Sort Item");
    JButton viewAllItems = new JButton("View AllItem");

    JLabel label = new JLabel(
            "<HTML><FONT FACE = ARIALSIZE = 2><B>Use The options below and In The Menu To Manage Stock");
    // Add Action Listeners
    addItem.addActionListener(this);
    deleteItem.addActionListener(this);
    searchItem.addActionListener(this);
    sortItem.addActionListener(this);
    viewAllItems.addActionListener(this);
    topPanel.add(label);
    bottomPanel.add(addItem);
    bottomPanel.add(deleteItem);
    bottomPanel.add(searchItem);
    bottomPanel.add(sortItem);
    bottomPanel.add(viewAllItems);
    frame.getContentPane().add(topPanel, BorderLayout.NORTH);
    frame.getContentPane().add(bottomPanel, BorderLayout.SOUTH);
    frame.setResizable(false);

}

public void actionPerformed(ActionEvent ae) {
    if (ae.getActionCommand() == "Add New Item") {
        //totalPrice = unitPrice * qty;
        // txtTotalPrice= totalPrice;
        addNewItem();

    }

    else if (ae.getActionCommand() == "Search Item") {
        searchItem();

    }

    else if (ae.getActionCommand() == "Sort Contacts") {
        sortItems();

    }

    else if (ae.getActionCommand() == "Delete Item") {
        deleteItem();

    }

    else if (ae.getActionCommand() == "View All Items") {

        viewAllItemsInStock();

    }

    else if (ae.getActionCommand() == "About") {
        JOptionPane.showMessageDialog(frame,
         "About StockManager:Helps to manage the stock by adding,deleting,searching and displaying items in the stock,",null, JOptionPane.INFORMATION_MESSAGE);

    } else if (ae.getActionCommand() == "Help Contents") {
        showHelp();

    } else if (ae.getActionCommand() == "Backup Contacts") {
        JFileChooser chooser = new JFileChooser();
        chooser.setCurrentDirectory(new File("."));
        chooser.setMultiSelectionEnabled(false);

        chooser.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
        chooser.showSaveDialog(frame);
        FileOutputStream bfout = null;
        FileInputStream bfin = null;
        String filename = null;

        int p;

        try {
            filename = chooser.getSelectedFile().getPath();
        } catch (Exception e) {
        }

        try {
            bfout = new FileOutputStream(filename + "/data.dat");
        } catch (Exception e) {

        }
        try {
            bfin = new FileInputStream("data/data.dat");
        } catch (Exception e) {

        }

        try {
            do {
                p = bfin.read();
                if (p != -1)
                    bfout.write(p);
            } while (p != -1);
        } catch (Exception e) {

        }

    }

}

private void showHelp() {
    // TODO Auto-generated method stub

}

private void viewAllItemsInStock() {
    /*ResultSet rs= st.executeQuery("Select * from test");
    ResultSetMetaData md = rs.getMetaData();
    int columns = md.getColumnCount();
    for (int i = 1; i <= columns; i++) {
    columnNames.addElement( md.getColumnName(i) );
    }
    while (rs.next()) {
    Vector row = new Vector(columns);
    for (int i = 1; i <= columns; i++) {
    row.addElement( rs.getObject(i) );
    }
    data.addElement( row );
    }
    rs.close();
    st.close();
    }
    catch(Exception e) {}
    JFrame tab=new JFrame();
    JTable table = new JTable(data, columnNames);
    JScrollPane scrollPane = new JScrollPane( table );
    tab.add( scrollPane );
    tab.setVisible(true); 
    tab.setSize(300,100);
    }
    });
    }*/

}

private void deleteItem() {
    // TODO Auto-generated method stub

}

private void sortItems() {
    // TODO Auto-generated method stub

}

private void searchItem() {
    // TODO Auto-generated method stub

}

public void addItemFrame() {
    JFrame newFrame;
    newFrame = new JFrame("Add New");
    newFrame.setSize(220, 250);
    newFrame.setResizable(false);
    newFrame.setIconImage(img);

    JLabel lblEntryDate = new JLabel("Item EntryDate: ");
    JLabel lblItemNo = new JLabel("Item No: ");
    JLabel lblItemName = new JLabel("Item Name: ");
    JLabel lblUnitPrice = new JLabel("Item UnitPrice: ");
    JLabel lblQty = new JLabel("Item Qty: ");
    JLabel lblTotalPrice = new JLabel("Item TotalPrice: ");
    JLabel lblSupplier = new JLabel("SupplierDetails: ");
    JLabel lblRemarks = new JLabel("Remarks: ");
    JLabel lblEmpty1 = new JLabel("");
    JLabel lblEmpty2 = new JLabel("");

    txtEntryDate = new JTextField(10);
    txtItemNo = new JTextField(10);
    txtItemName = new JTextField(10);
    txtUnitPrice = new JTextField(10);
    txtQty = new JTextField(10);
    txtTotalPrice = new JTextField(10);
    txtSupplier = new JTextField(10);
    txtRemarks = new JTextField(10);

    JButton bttnAdd = new JButton("Save");
    JButton bttnCancel = new JButton("Save Added!");

    bttnAdd.addActionListener(this);
    bttnCancel.addActionListener(this);

    JPanel centerPane = new JPanel();
    JPanel bottomPane = new JPanel();

    centerPane.add(lblEntryDate);
    centerPane.add(txtEntryDate);
    centerPane.add(lblItemNo);
    centerPane.add(txtItemNo);
    centerPane.add(lblItemName);
    centerPane.add(txtItemName);
    centerPane.add(lblUnitPrice);
    centerPane.add(txtUnitPrice);
    centerPane.add(lblQty);
    centerPane.add(txtQty);
    centerPane.add(lblTotalPrice);
    centerPane.add(txtTotalPrice);
    centerPane.add(lblSupplier);
    centerPane.add(txtSupplier);
    centerPane.add(lblRemarks);
    centerPane.add(txtRemarks);
    bottomPane.add(bttnAdd);
    bottomPane.add(bttnCancel);
    centerPane.setLayout(new GridLayout(0, 2));

    newFrame.getContentPane().add(centerPane, BorderLayout.CENTER);

    newFrame.getContentPane().add(bottomPane, BorderLayout.SOUTH);
    newFrame.setLocation(screenWidth / 4, screenHeight / 4);
    newFrame.show();

}

public void addNewItem() {
    addItemFrame();
    entryDate = txtEntryDate.getText();
    itemNo = Integer.parseInt(txtItemNo.getText());
    itemName = txtItemName.getText();
    unitPrice = Double.parseDouble(txtUnitPrice.getText());
    qty = Double.parseDouble(txtQty.getText());
    totalPrice = unitPrice * qty;
    supplier = txtSupplier.getText();
    remarks = txtRemarks.getText();

    if (itemName.equals("")) {
        JOptionPane.showMessageDialog(null, "Please enter Item name.");
    }
    if (txtUnitPrice.getText() == "") {
        JOptionPane.showMessageDialog(null,
                "Please enter UnitPrice for the item");
    }
    if (txtQty.getText() == "") {
        JOptionPane.showMessageDialog(null,
                "Please enter Quantity of item to be added");
    } else {

        Items item = new Items(entryDate, itemNo, itemName, unitPrice, qty,
                totalPrice, supplier, remarks);
        stockManagerDAO.addNewItem(item);
        JOptionPane.showMessageDialog(null, "Person Saved");
    }
}

}

Items.java

public class Items
{
  String entryDate;
   int itemNo;
   String itemName;
   double unitPrice;
   double qty;
   double totalPrice;
   String supplier;
   String remarks;

  // default constructor
  public Items()
  {       
    entryDate ="" ;
    itemNo = 0;
    itemName="";
    unitPrice=0;
    qty=0;
    totalPrice=0;
    supplier="";
   remarks="";
  }

public Items(String entryDate,int itemNo,String itemName,double unitPrice,double qty,double totalPrice,String supplier,String remarks)
{
    this.entryDate = entryDate;
    this.itemNo = itemNo;
    this.itemName = itemName;
    this.unitPrice = unitPrice;
    this.qty =qty;
    this.totalPrice=totalPrice;
    this.supplier=supplier;
    this.remarks=remarks;
} 
//getter and setter methods
   }

StockManagerDAO.java

package org.bil.service;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Vector;

import javax.swing.ButtonGroup;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

import org.res.bil.PersonInfo;



class StockManagerDAO
{
private ArrayList itemList;
private String userid = "root";
private String password = "sa";
static String url = "jdbc:mysql://localhost/test";; 
private Connection con;

public void StockManagerDAO()
{
    itemList = new ArrayList();
    getConnection();        //Create Connection to the Oracle Database
}

public Connection getConnection(){

    try {
        Class.forName("com.mysql.jdbc.Driver"); 

    } catch(java.lang.ClassNotFoundException e) {
        System.err.print("ClassNotFoundException: ");
        System.err.println(e.getMessage());
    }

    try {
        con = DriverManager.getConnection(url, userid, password);
    } catch(SQLException ex) {
        System.err.println("SQLException: " + ex.getMessage());
    }

    return con;
}

/*public ArrayList searchItem(String name)
{
    try {
        String sql = "SELECT * FROM Item WHERE name like '%"+name+"%'";

        // Create a prepared statement
        Statement s = con.createStatement();

        ResultSet rs = s.executeQuery(sql);

        String itemname = "";
        String itemno = "";
       ........

        while(rs.next())
        {
            id = rs.getInt("id");
            pname = rs.getString("name");
            address = rs.getString("address");
            phone = rs.getInt("phone");
            email = rs.getString("email");

            //Create a Item object
            PersonInfo person = new PersonInfo(id, pname, address, phone, email);

            //Add the person object to array list
            personsList.add(person);
        }
    }
    catch(Exception e){
        System.out.println(e);
    }

    return personsList;
} 
*/
public void addNewItem(Items item) {

    try
    {

        String sql = "INSERT INTO stock(ItemNo ,ItemEntryDate, ItemName, ItemUnitPrice, ItemQty, ItemTotalPrice,ItemSupplier, ItemRemarks) VALUES (?,?,?,?,?,?,?,?) ";

        // Create a Preparedstatement
        PreparedStatement ps = con.prepareStatement(sql);

        ps.setInt(1,item.getItemNo());
        ps.setString(2, item.getEntryDate());
        ps.setString(3, item.getItemName());
        ps.setDouble(4, item.getUnitPrice());
        ps.setDouble(5, item.getQty());
        ps.setDouble(6, item.getTotalPrice());
        ps.setString(7, item.getSupplier());
        ps.setString(8, item.getRemarks());

        ps.executeUpdate();
    }
    catch(Exception e){
        System.out.println(e);
    }
// TODO Auto-generated method stub

}

}

..Please help me…

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1 Answer

Editorial Team · Answer 1 · 2026-06-04T04:32:37+00:00

Editorial Team

2026-06-04T04:32:37+00:00Added an answer on June 4, 2026 at 4:32 am

It looks like you are trying to parse an empty string ("") as an integer (in Integer.parseInt(txtItemNo.getText()) in StockManager.addNewItem()).

You will either need to ensure that the contents of txtItemNo is not empty or, better yet, catch the NumberFormatException when an invalid string is parsed.

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