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问一个JAVA编程题

wwwhahchn

发贴: 5
积分: 0

于 2006-05-06 12:28

编写程序，计算销售总额和提成，如图所示。用户在Sales Amount文本域中键入销售总额并按下回车键后，Commissions文本域中显示提成。类似的，用户键入提成后，显示相应的销售总额。

我写的程序：
import java.awt.GridLayout;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.border.TitledBorder;

public class Exercise_9_10 extends JFrame implements ActionListener
{
private JTextField jtfSalesAmount, jtfCommissions;

public static void main(String[] args)
{
Exercise_9_10 frame = new Exercise_9_10();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}

public Exercise_9_10()
{
setTitle("Exercise 9.10");

JLabel jlblInputSalesAmount = new JLabel("Sales Amount");
JLabel jlblInputCommissions = new JLabel("Commissions");
JLabel jlblSalesAmount = new JLabel("Sales Amount");
JLabel jlblCommissionRate = new JLabel("Commission Rate");
JLabel jlblSA1 = new JLabel("$1 to $5,000");
JLabel jlblSA2 = new JLabel("$5,000 to $10,000");
JLabel jlblSA3 = new JLabel("Above $10,000");
JLabel jlblCR1 = new JLabel("8 Percent");
JLabel jlblCR2 = new JLabel("10 Percent");
JLabel jlblCR3 = new JLabel("12 Percent");

jtfSalesAmount = new JTextField(15);
jtfCommissions = new JTextField(15);

JPanel p1 = new JPanel();
p1.setLayout(new GridLayout(2, 2));
p1.add(jlblInputSalesAmount);
p1.add(jtfSalesAmount);
p1.add(jlblInputCommissions);
p1.add(jtfCommissions);
p1.setBorder(new TitledBorder("Sales Amount and Commissions"));

JPanel p2 = new JPanel();
p2.setLayout(new GridLayout(4, 2));
p2.add(jlblSalesAmount);
p2.add(jlblCommissionRate);
p2.add(jlblSA1);
p2.add(jlblCR1);
p2.add(jlblSA2);
p2.add(jlblCR2);
p2.add(jlblSA3);
p2.add(jlblCR3);
p2.setBorder(new TitledBorder("Commission Rate"));

getContentPane().setLayout(new BorderLayout());
getContentPane().add(p1, BorderLayout.CENTER);
getContentPane().add(p2, BorderLayout.SOUTH);

jtfSalesAmount.addActionListener(this);
jtfCommissions.addActionListener(this);
}

public void actionPerformed(ActionEvent e)
{
double salesAmount, commission;

if (e.getSource() == jtfSalesAmount)
if (jtfSalesAmount.getText().trim() != null)
{
salesAmount = Double.parseDouble(jtfSalesAmount.getText().trim());

if (salesAmount > 10000)
commission = 5000*0.08+5000*0.1+(salesAmount-10000)*0.12;
else if (salesAmount > 5000)
commission = 5000*0.08+(salesAmount-5000)*0.1;
else
commission = salesAmount*0.08;

jtfCommissions.setText(String.valueOf(commission));
}
else if (e.getSource() == jtfCommissions)
if (jtfCommissions.getText().trim() != null)
{
commission = Double.parseDouble(jtfCommissions.getText().trim());

if (commission > 900)
salesAmount = 10000+(commission-900)/0.12;
else if (commission > 400)
salesAmount = 5000+(commission-400)/0.10;
else
salesAmount = commission/0.08;

jtfSalesAmount.setText(String.valueOf(salesAmount));
}
}
}

现在运行的结果就是，可以做到“用户在Sales Amount文本域中键入销售总额并按下回车键后，Commissions文本域中显示提成”，但是做不到“用户键入提成后，显示相应的销售总额”，键入提成后按下回车键，程序没反应

偶不知道问题出在哪里，请NN帮忙看一下，3q

wwwhahchn edited on 2006-05-06 12:33

• 关于女孩子从事软件开发的问题

作者

Re:问一个JAVA编程题 [Re:wwwhahchn]

sunjavaduke

乒乓球国手-张怡宁

发贴: 176
积分: 6

于 2006-05-06 13:21

import java.awt.GridLayout;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.JLabel;
import javax.swing.border.TitledBorder;

public class Exercise_9_10 extends JFrame implements ActionListener
{
private JTextField jtfSalesAmount, jtfCommissions;

public static void main(String[] args)
{
Exercise_9_10 frame = new Exercise_9_10();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}

public Exercise_9_10()
{
setTitle("Exercise 9.10");

JLabel jlblInputSalesAmount = new JLabel("Sales Amount");
JLabel jlblInputCommissions = new JLabel("Commissions");
JLabel jlblSalesAmount = new JLabel("Sales Amount");
JLabel jlblCommissionRate = new JLabel("Commission Rate");
JLabel jlblSA1 = new JLabel("$1 to $5,000");
JLabel jlblSA2 = new JLabel("$5,000 to $10,000");
JLabel jlblSA3 = new JLabel("Above $10,000");
JLabel jlblCR1 = new JLabel("8 Percent");
JLabel jlblCR2 = new JLabel("10 Percent");
JLabel jlblCR3 = new JLabel("12 Percent");

jtfSalesAmount = new JTextField(15);
jtfCommissions = new JTextField(15);

JPanel p1 = new JPanel();
p1.setLayout(new GridLayout(2, 2));
p1.add(jlblInputSalesAmount);
p1.add(jtfSalesAmount);
p1.add(jlblInputCommissions);
p1.add(jtfCommissions);
p1.setBorder(new TitledBorder("Sales Amount and Commissions"));

JPanel p2 = new JPanel();
p2.setLayout(new GridLayout(4, 2));
p2.add(jlblSalesAmount);
p2.add(jlblCommissionRate);
p2.add(jlblSA1);
p2.add(jlblCR1);
p2.add(jlblSA2);
p2.add(jlblCR2);
p2.add(jlblSA3);
p2.add(jlblCR3);
p2.setBorder(new TitledBorder("Commission Rate"));

getContentPane().setLayout(new BorderLayout());
getContentPane().add(p1, BorderLayout.CENTER);
getContentPane().add(p2, BorderLayout.SOUTH);

jtfSalesAmount.addActionListener(this);
jtfCommissions.addActionListener(this);
}

public void actionPerformed(ActionEvent e)
{
double salesAmount, commission;

if (e.getSource() == jtfSalesAmount)
{
if (jtfSalesAmount.getText().trim() != null)
{
salesAmount = Double.parseDouble(jtfSalesAmount.getText().trim());

if (salesAmount > 10000)
commission = 5000*0.08+5000*0.1+(salesAmount-10000)*0.12;
else if (salesAmount > 5000)
commission = 5000*0.08+(salesAmount-5000)*0.1;
else
commission = salesAmount*0.08;

jtfCommissions.setText(String.valueOf(commission));
}
}
else if (e.getSource() == jtfCommissions)
{
if (jtfCommissions.getText().trim() != null)
{
commission = Double.parseDouble(jtfCommissions.getText().trim());

if (commission > 900)
salesAmount = 10000+(commission-900)/0.12;
else if (commission > 400)
salesAmount = 5000+(commission-400)/0.10;
else
salesAmount = commission/0.08;

jtfSalesAmount.setText(String.valueOf(salesAmount));
}
}
}
}

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mail:zhangzhongl@neusoft.com
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• 关于异常。。。。谢谢指教

作者

Re:问一个JAVA编程题 [Re:wwwhahchn]

sunjavaduke

乒乓球国手-张怡宁

发贴: 176
积分: 6

于 2006-05-06 13:27

现在可以运行了
说明
在事件处理中public void actionPerformed(ActionEvent e)
{
你的if语句是有问题的，也就是说，当事件发生的初识对象是jtfSalesAmount时，执行下面的操作，由于if语句没有些语句块的标志{}，所以if的体为紧跟着它的那一条语句，即下一个
if (jtfSalesAmount.getText().trim() != null)
{
salesAmount = Double.parseDouble(jtfSalesAmount.getText().trim());

if (salesAmount > 10000)
commission = 5000*0.08+5000*0.1+(salesAmount-10000)*0.12;
else if (salesAmount > 5000)
commission = 5000*0.08+(salesAmount-5000)*0.1;
else
commission = salesAmount*0.08;

jtfCommissions.setText(String.valueOf(commission));
}

下面你就应该懂了，if-----else if的配对原则你应该知道吧，所以elseif是与你的内层的if配对，而不是与判断是否事件发生对象那个if配对
}
还有，建议你对输入框中输入为空时进行一下处理，否则会有异常发生，造成程序停止，比如给出用户提示“输入为空”，或者输入为空时，将提成设置成0。
建议而已。

• 如何用JTable设置表头多行

作者	Re:问一个JAVA编程题 [Re:wwwhahchn]
wwwhahchn 发贴: 5 积分: 0	于 2006-05-06 14:33 哇，非常感谢，原来是配对出问题了，这下明白了你的建议很对，我还是初学，没注意到，谢谢严重感谢 • 加入CJSDN真好!

作者	Re:问一个JAVA编程题 [Re:wwwhahchn]
sunjavaduke 乒乓球国手-张怡宁发贴: 176 积分: 6	于 2006-05-06 15:10 learn from each other~ ----------------------------------------------------------------- icd.Neusoft Co,.Ltd. mail:zhangzhongl@neusoft.com tel:13591718127 QQ:176932855 ------------------------------------------------------------------ • Eclipse開發平台快速入門

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