运行显示错误Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: em

[m0_46168308]

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

@SuppressWarnings("serial")
public class Swing extends JFrame implements ActionListener{
private JLabel j1;
private JLabel j2;
private JLabel j3;

private JTextField txtdata1;
private JTextField txtdata2;
private JRadioButton radioM,radioF;
private JTextArea txtShow;
private JButton btnAdd;
private JButton btnReset;
private JButton btnSelect;
private Box boxHone,boxHtwo,boxHs;
private Box boxVone,boxVtwo,boxVthree;
private ButtonGroup group;
private JComboBox<String> comBox;

public Swing() {
init();
this.setVisible(true);
this.setSize(800, 400);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
this.setLayout(new FlowLayout());
}

void init() {
boxHone=Box.createHorizontalBox();
boxHtwo=Box.createHorizontalBox();
boxHs=Box.createHorizontalBox();
boxVone=Box.createVerticalBox();
boxVtwo=Box.createVerticalBox();
boxVthree=Box.createVerticalBox();
j1=new JLabel("num:");
j2=new JLabel("name:");
j3=new JLabel("sex:");
txtdata1=new JTextField(30);
txtdata2=new JTextField(30);
radioM=new JRadioButton("man");
radioF=new JRadioButton("woman");
group=new ButtonGroup();
comBox=new JComboBox<String>();
group.add(radioM); //归组实现单选；
group.add(radioF);
txtShow=new JTextArea(9,30);
btnAdd=new JButton("增加");
btnReset=new JButton("重置");
btnSelect=new JButton("查询");
comBox.addItem("Chairman");
comBox.addItem("GM");
comBox.addItem("BM");
comBox.addItem("employee");
boxVtwo.add(j1); //boxVtwo三个标签的列盒子；
boxVtwo.add(Box.createVerticalStrut(3));
boxVtwo.add(j2);
boxVtwo.add(Box.createVerticalStrut(5));
boxVtwo.add(j3);
boxVthree.add(txtdata2);
boxVthree.add(txtdata1); //boxVthree二个文本框和性别选择的列盒子；
boxHs.add(radioM);
boxHs.add(radioF);
boxVthree.add(boxHs);
boxHone.add(boxVtwo);
boxHone.add(boxVthree);
boxVone.add(boxHone);
boxHtwo.add(comBox);//boxHtwo三个按钮和下拉菜单的行盒子
boxHtwo.add(Box.createHorizontalStrut(40));
boxHtwo.add(btnAdd);
boxHtwo.add(Box.createHorizontalStrut(10));
boxHtwo.add(btnReset);
boxHtwo.add(Box.createHorizontalStrut(10));
boxHtwo.add(btnSelect);
btnSelect.addActionListener(this);
boxVone.add(boxHtwo);
add(boxVone);
boxVone.add(txtShow); //最下面的显示区域；


}

@SuppressWarnings("unused")
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
String strDriver = "com.mysql.jdbc.Driver";
try {
System.out.println("加载驱动程序...");
System.out.println("驱动程序字符串：" + strDriver);
Class.forName(strDriver);
System.out.println("驱动程序加载成功");
} catch (Exception e1) {
System.out.println("驱动程序加载失败");
}

Connection conDatabase = null;
String strURL = "jdbc:mysql://localhost:3306/t_test8?useUnicode=true&characterEncoding=UTF-8";
try {
System.out.println("连接数据库...");
System.out.println("数据库URL：" + strURL);
conDatabase = DriverManager.getConnection(strURL, "root", "123456");
System.out.println("数据库连接成功");
} catch (SQLException e1) {
if (conDatabase != null) {
try {
conDatabase.close();
} catch (SQLException e2) {
e2.printStackTrace();
}
}
System.out.println("数据库连接失败");
e1.printStackTrace();
return;
}

Statement dbState = null;
ResultSet dbRS = null;
try {
dbState = conDatabase.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_UPDATABLE);
String sql="select * from t_test8 ";
dbState.execute(sql);
dbRS = dbState.getResultSet();
System.out.println("表读取成功");
} catch (SQLException e1) {
System.out.println("表读取失败");
e1.printStackTrace();
}

try {
while (dbRS.next()) {
int c1 = dbRS.getInt("num");
String c2 = dbRS.getString("name");
String c3 = dbRS.getString("sex");
String c4 = dbRS.getString("post");
Float d1=Float.valueOf(txtdata1.getText());
JButton btn=(JButton)e.getSource();
if(btn.getText().equals("查询"))
if(d1==c1)
txtShow.append(c1+" "+c2+" "+c3+" "+c4+"\n");
}
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}

try {
conDatabase.close();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
}



运行结果：
驱动程序字符串：com.mysql.jdbc.Driver
驱动程序加载成功
连接数据库...
数据库URL：jdbc:mysql://localhost:3306/t_test8?useUnicode=true&characterEncoding=UTF-8
数据库连接成功
表读取成功
Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
at sun.misc.FloatingDecimal.parseFloat(Unknown Source)
at java.lang.Float.parseFloat(Unknown Source)
at java.lang.Float.valueOf(Unknown Source)
at Swing.actionPerformed(Swing.java:142)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

[时光呢]

你看下你报错那一行，是不是string没有判空，就直接断数字了