我的问题是，当我选择单选按钮时，它会在 java 终端中导致巨大的错误。它在开始按钮（按钮1到按钮4）中，按钮1启动加油站（这样你就可以选择你想要的汽油类型），但它没有打开单选按钮可供选择，而是给了我一堆错误，与
有关Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: empty String
单选按钮之前可以工作，但是在我使用复选框方法之后，它停止工作，但是复选框选择有效（但是没有清除）。 发现错误了，就属于这个
litres=Double.parseDouble(gasL.getText());
所以我暂时删除了该部分，但不确定如何让它工作，因为我试图从用户可以输入的文本框中获取升数。煤气吧还没打开
清除适用于复选框，但我不确定单选按钮，这给了我错误
这是我的代码
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
/**
* A GUI for a Gas Bar, which allows you to choose the gas type you want, and optional car checks for things like
* windshield and gas check. The price is outputted afterwards.
*
* @author Kevin Hy
* @date 08/06/13
*/
public class New_Gas_Bar extends JFrame
{
public JPanel panel1,panel2,panel3,panel4,panel5;
public JLabel main1, main2, main3,main4,main5,main6;
public JLabel gasBar,total;
public JButton button1,button2,button3,button4,clearGas,clearCar;
public JRadioButton bronzeG,silverG,goldG,selfS,fullS,fullService,selfService;
public JCheckBox oilC,windWash,pressureClock;
public JTextField gasL;
static double fullCost,selfCost,discount,gasCost,litres,cleaningC;
static boolean boughtGas=false;
public New_Gas_Bar()
{
super (" New Gas Bar");
setSize(640,640);
Container container = getContentPane();
panel1=new JPanel();
panel2=new JPanel();
panel3=new JPanel();
panel4=new JPanel();
panel5=new JPanel();
panel1.setBackground(new Color(107,202,226));
panel1.setLayout(new GridLayout(6,1));
main1 = new JLabel (" Gas Bar Project ");
main2 = new JLabel (" ICS4U0 - September 2013");
main3 = new JLabel (" ");
main4 = new JLabel ("Enter Litres of Gas");
main5 = new JLabel ("Select Full or Self Serve");
main6 = new JLabel ("Select Gas Quality");
button1 = new JButton ("Gas Station");
button2 = new JButton ("Car Wash");
button3 = new JButton ("Total");
button4 = new JButton ("Exit");
clearCar = new JButton ("Clear");
clearGas = new JButton ("Clear");
panel2.setBackground(new Color(144,160,170));
panel2.setLayout(new FlowLayout ());
panel2.add (button1);
panel2.add (button2);
panel2.add (button3);
panel2.add (button4);
panel1.add (main1);
panel1.add (main2);
panel1.add (main3);
//container.setLayout(new BorderLayout());
container.add(panel1,BorderLayout.NORTH);
container.add(panel2,BorderLayout.CENTER);
container.add(panel3,BorderLayout.EAST);
container.add(panel4,BorderLayout.EAST);
panel3.setBackground(new Color(107,202,226));
panel4.setBackground(new Color(107,202,226));
ButtonHandler handler = new ButtonHandler ();
button1.addActionListener (handler);
button2.addActionListener (handler);
button3.addActionListener (handler);
button4.addActionListener (handler);
clearCar.addActionListener (handler);
clearGas.addActionListener (handler);
ButtonGroup serveStyle = new ButtonGroup();
fullS = new JRadioButton ("Full Serve");
selfS = new JRadioButton ("Self Serve");
serveStyle.add (fullS);
serveStyle.add (selfS);
ButtonGroup serveGas = new ButtonGroup();
bronzeG = new JRadioButton("Bronze Service");
silverG = new JRadioButton("Silver Service");
goldG = new JRadioButton("Gold Service");
serveGas.add (bronzeG);
serveGas.add (silverG);
serveGas.add (goldG);
gasL = new JTextField(5);
oilC = new JCheckBox("Oil Change");
windWash = new JCheckBox("Windshield Wash");
pressureClock = new JCheckBox("Air Pressure Check");
RadioButtonHandler radioHand = new RadioButtonHandler ();
bronzeG.addItemListener (radioHand);
silverG.addItemListener (radioHand);
goldG.addItemListener (radioHand);
fullS.addItemListener (radioHand);
selfS.addItemListener (radioHand);
CheckBoxHandler checkHand = new CheckBoxHandler();
oilC.addItemListener (checkHand);
windWash.addItemListener (checkHand);
pressureClock.addItemListener (checkHand);
setVisible(true);
}
public static void main (String [] args)
{
New_Gas_Bar application = new New_Gas_Bar();
}
public class ButtonHandler implements ActionListener
{
public void actionPerformed (ActionEvent event)
{
if (event.getSource () == button1)
{
panel1.setVisible(true);
panel2.setVisible(true);
panel3.setVisible(true);
panel4.setVisible(false);
panel3.setLayout(new GridLayout(10,1));
panel3.add(clearGas);
panel3.add(main5);
panel3.add(fullS);
panel3.add(selfS);
panel3.add(main6);
panel3.add(bronzeG);
panel3.add(silverG);
panel3.add(goldG);
panel3.add(main4);
panel3.add(gasL);
litres=Double.parseDouble(gasL.getText());
//JOptionPane.showMessageDialog (null, litres);
}
else if (event.getSource () == button2)
{
panel1.setVisible(true);
panel2.setVisible(true);
panel3.setVisible(false);
panel4.setVisible(true);
panel4.setLayout(new FlowLayout ());
panel4.add(clearCar);
panel4.add(oilC);
panel4.add(windWash);
panel4.add(pressureClock);
}
else if (event.getSource () == button3)
{
JOptionPane.showMessageDialog (null, "This is your total:");
JOptionPane.showMessageDialog (null, litres);
}
else if (event.getSource () == button4)
{
System.exit(0);
}
if (event.getSource () == clearGas)
{
JOptionPane.showMessageDialog (null, "Clearing All Selected Options");
bronzeG.setSelected(false);
silverG.setSelected(false);
goldG.setSelected(false);
fullS.setSelected(false);
selfS.setSelected(false);
gasCost=0;
boughtGas=false;
}
if (event.getSource () == clearCar)
{
JOptionPane.showMessageDialog (null, "Clearing All Selected Options");
pressureClock.setSelected(false);
windWash.setSelected(false);
oilC.setSelected(false);
cleaningC=0;
}
}
}
public class RadioButtonHandler implements ItemListener
{
public void itemStateChanged(ItemEvent event)
{
if (event.getSource () == fullS)
{
JOptionPane.showMessageDialog (null, "Full Serve Selected");
fullCost =1.25;
boughtGas=true;
}
else if (event.getSource () == selfS)
{
JOptionPane.showMessageDialog (null, "Self Serve Selected");
selfCost =0.60;
boughtGas=true;
}
if (event.getSource () == bronzeG)
{
JOptionPane.showMessageDialog (null, "Bronze Gas Option Selected");
gasCost=0.50;
boughtGas=true;
}
if (event.getSource () == silverG)
{
JOptionPane.showMessageDialog (null, "Silver Gas Option Selected");
gasCost=0.75;
boughtGas=true;
}
if (event.getSource () == goldG)
{
JOptionPane.showMessageDialog (null, "Gold Gas Option Selected");
gasCost=0.95;
boughtGas=true;
}
}
}
public class CheckBoxHandler implements ItemListener
{
public void itemStateChanged (ItemEvent event)
{
if (event.getSource () == oilC)
{
JOptionPane.showMessageDialog (null, "Oil Cleaning Selected");
if (boughtGas==true)
{
cleaningC+=10.00;
}
else
{
cleaningC+=12.50;
}
}
if (event.getSource () == windWash)
{
JOptionPane.showMessageDialog (null, "Windshield Washing Selected");
if (boughtGas==true)
{
cleaningC+=10.00;
}
else
{
cleaningC+=12.50;
}
}
if (event.getSource () == pressureClock)
{
JOptionPane.showMessageDialog (null, "Air Pressure Check Selected");
if (boughtGas==true)
{
cleaningC+=10.00;
}
else
{
cleaningC+=12.50;
}
}
}
}
}
我认为最好不使用以下方法：Double.parseDouble()直接。
当然，您不会想开发自己的方法来解析双精度数等。
我喜欢做的是将空字符串甚至空值映射为零。
public static double myParseDouble(String s) {
if (s == null || s.equals("")) {
return 0.0;
} else {
return Double.parseDouble(s);
}
}
在解析 int、float、long 和 BigIntegers 时，您必须执行相同的操作。
我建议您在自己的项目中采用我的方法，并“使用它”，通过它运行各种字符串，看看它会做什么。
查看您收到的错误。它说 NumberFormatException。我相信问题出在你的 Double.parseDouble(gasL.getText()) 上。当gasL留空时会发生什么？程序如何将空字符串解析为双精度字符串？尝试将 GasL 的默认值设置为 0 或查看 try/catch 来处理异常。
gasL = new JTextField("0",5);
这会删除错误消息，但我无法弄清楚为什么您的加油站面板未打开。