我正在尝试使用MySQL在java swing中开发一个stockManager应用程序。运行代码我遇到了以下错误：
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)
我附上下面的代码......有点长......请原谅..
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
}
}
..请帮帮我......
答案 0 :(得分：1)
看起来您正在尝试将空字符串（""）解析为整数（Integer.parseInt(txtItemNo.getText())中的StockManager.addNewItem()）。
您需要确保txtItemNo的内容不为空，或者更好的是，在解析无效字符串时捕获NumberFormatException。
答案 1 :(得分：1)
这意味着你的txtItemNo没有文本，在解析它之前检查它并在它无效时显示错误（或捕获异常并在catch块中显示错误）