java编写的简单的计算器程序(共22页)

1、计算器项目内容：编写一个Applet，模仿windows附件所带计算器的功能，可以帮助用户完成计算功能，具体如下图所示。项目要求：使用图形的方式借助窗口、菜单、按钮等标准界面元素和鼠标操作，来帮助用户方便地向计算机系统发出命令，启动操作，并将系统运行的结果同样以图形的方式显示给用户，这样更加直观和生动； 1. Applet容器中组件的添加与设置，包括面板以及菜单的使用； 2. 容器中组件的布局管理； 3. Java核心包中数组、数学计算类的使用； 4. 异常的处理； 5. 事件处理模型中的三类对象的使用： 1. Event-事件，用户对界面操作在java语言上的描述，以类的形式出现，例如键盘操

2、作对应的事件类是KeyEvent。 2. Event Source-事件源，事件发生的场所，通常就是各个组件，例如按钮Button。 3. Event handler-事件处理者，接收事件对象并对其进行处理的对象。 6. 程序中事件处理的流程：1. 计算流程的细化 参考代码：import java.awt.*;import java.lang.*;import javax.swing.*;import javax.swing.event.*;import java.awt.event.*;import java.text.DecimalFormat;public class Calculato

3、r implements ActionListener /导入动作监听接口 /设计面板中的单位 JFrame frame; JTextField textAnswer; JPanel panel, panel1, panel2, panel3; JMenuBar mainMenu; JTextField textMemory; JLabel labelMemSpace; /labelMemSpace单纯做摆设，控制面板的形状 JButton buttonBk, buttonCe, buttonC; JButton button; JButton buttonMC, buttonMR, butt

4、onMS, buttonMAdd; JButton buttonDot, buttonAddAndSub, buttonAdd, buttonSub, buttonMul, buttonDiv, buttonMod; JButton buttonSqrt, buttonDao, buttonEqual; JMenu editMenu, viewMenu, helpMenu; JMenuItem copyItem, pasteItem, tItem, sItem, numberGroup, topHelp, aboutCal; DecimalFormat df; /设置数据输出精度 boolea

5、n clickable; /控制当前能否按键 double memoryd; /使用内存中存储的数字 int memoryi; double vard, answerd; /用来保存double型数据的中间值(vard)和最后结果(answerd) short key = -1, prekey = -1; /key用来保存当前进行何种运算,prekey用来保存前次进行何种运算 String copy; /做复制用 JTextArea help; /帮助 JScrollPane scrollHelp; /构造函数 public Calculator() clickable = true; ans

6、werd = 0; frame = new JFrame(计算器); df = new DecimalFormat(0.#); /设置数据输出精度(对于double型值) textAnswer = new JTextField(15); textAnswer.setText(); textAnswer.setEditable(false); textAnswer.setBackground(new Color(255, 255, 255); panel = new JPanel(); frame.getContentPane().add(panel); panel1 = new JPanel(

7、); panel2 = new JPanel(); panel.setLayout(new BorderLayout(); /设计整个面板 mainMenu = new JMenuBar(); editMenu = new JMenu(编辑(E); viewMenu = new JMenu(查看(V); helpMenu = new JMenu(帮助(H); copyItem = new JMenuItem( 复制(C) Ctrl+C); copyItem.addActionListener(this); pasteItem = new JMenuItem( 粘贴(V) Ctrl+V); pa

8、steItem.addActionListener(this); editMenu.add(copyItem); editMenu.add(pasteItem); tItem = new JMenuItem(标准型(T); tItem.addActionListener(this); sItem = new JMenuItem( 科学型(S); sItem.addActionListener(this); numberGroup = new JMenuItem( 数字分组(I); numberGroup.addActionListener(this); viewMenu.add(tItem);

9、 viewMenu.add(sItem); viewMenu.add(numberGroup); topHelp = new JMenuItem( 帮助主题(H); topHelp.addActionListener(this); help = new JTextArea(5, 20); scrollHelp = new JScrollPane(help); help.setEditable(false); help.append(执行简单计算n); help.append(1. 键入计算的第一个数字。n); help.append(2. 单击“+”执行加、“-”执行减、“*”执行乘或“/”执

10、行除。n); help.append(3. 键入计算的下一个数字。n); help.append(4. 输入所有剩余的运算符和数字。n); help.append(5. 单击“=”。n); aboutCal = new JMenuItem( 关于计算器(A); aboutCal.addActionListener(this); helpMenu.add(topHelp); helpMenu.add(aboutCal); mainMenu.add(editMenu); mainMenu.add(viewMenu); mainMenu.add(helpMenu); panel.add(mainMe

11、nu, BorderLayout.NORTH); panel.add(textAnswer, BorderLayout.CENTER); panel.add(panel1, BorderLayout.SOUTH); panel1.setLayout(new BorderLayout(); textMemory = new JTextField(3); textMemory.setEditable(false); textMemory.setBackground(new Color(217, 217, 217); labelMemSpace = new JLabel( ); buttonBk =

12、 new JButton(Backspace); buttonBk.setForeground(new Color(255, 0, 0); buttonCe = new JButton(CE); buttonCe.setForeground(new Color(255, 0, 0); buttonC = new JButton(C); buttonC.setForeground(new Color(255, 0, 0); buttonBk.addActionListener(this); buttonCe.addActionListener(this); buttonC.addActionLi

13、stener(this); panel1.add(panel2, BorderLayout.NORTH); panel2.setLayout(new FlowLayout(FlowLayout.RIGHT); panel2.add(textMemory); panel2.add(labelMemSpace); panel2.add(buttonBk); panel2.add(buttonCe); panel2.add(buttonC); panel3 = new JPanel(); panel1.add(panel3, BorderLayout.CENTER); button = new JB

14、utton10; for (int i = 0; i button.length; i+) buttoni = new JButton(Integer.toString(i); buttoni.setForeground(new Color(0, 0, 255); buttonMC = new JButton(MC); buttonMC.setForeground(new Color(255, 0, 0); buttonMR = new JButton(MR); buttonMR.setForeground(new Color(255, 0, 0); buttonMS = new JButto

15、n(MS); buttonMS.setForeground(new Color(255, 0, 0); buttonMAdd = new JButton(M+); buttonMAdd.setForeground(new Color(255, 0, 0); buttonDot = new JButton(.); buttonDot.setForeground(new Color(0, 0, 255); buttonAddAndSub = new JButton(+/-); buttonAddAndSub.setForeground(new Color(0, 0, 255); buttonAdd

16、 = new JButton(+); buttonAdd.setForeground(new Color(255, 0, 0); buttonSub = new JButton(-); buttonSub.setForeground(new Color(255, 0, 0); buttonMul = new JButton(*); buttonMul.setForeground(new Color(255, 0, 0); buttonDiv = new JButton(/); buttonDiv.setForeground(new Color(255, 0, 0); buttonMod = n

17、ew JButton(%); buttonMod.setForeground(new Color(0, 0, 255); buttonSqrt = new JButton(sqrt); buttonSqrt.setForeground(new Color(0, 0, 255); buttonDao = new JButton(1/x); buttonDao.setForeground(new Color(0, 0, 255); buttonEqual = new JButton(=); buttonEqual.setForeground(new Color(255, 0, 0); /将所有行为

18、与监听绑定 panel3.setLayout(new GridLayout(4, 6); panel3.add(buttonMC); buttonMC.addActionListener(this); panel3.add(button7); button7.addActionListener(this); panel3.add(button8); button8.addActionListener(this); panel3.add(button9); button9.addActionListener(this); panel3.add(buttonDiv); buttonDiv.addA

19、ctionListener(this); panel3.add(buttonSqrt); buttonSqrt.addActionListener(this); panel3.add(buttonMR); buttonMR.addActionListener(this); panel3.add(button4); button4.addActionListener(this); panel3.add(button5); button5.addActionListener(this); panel3.add(button6); button6.addActionListener(this); p

20、anel3.add(buttonMul); buttonMul.addActionListener(this); panel3.add(buttonMod); buttonMod.addActionListener(this); panel3.add(buttonMS); buttonMS.addActionListener(this); panel3.add(button1); button1.addActionListener(this); panel3.add(button2); button2.addActionListener(this); panel3.add(button3);

21、button3.addActionListener(this); panel3.add(buttonSub); buttonSub.addActionListener(this); panel3.add(buttonDao); buttonDao.addActionListener(this); panel3.add(buttonMAdd); buttonMAdd.addActionListener(this); panel3.add(button0); button0.addActionListener(this); panel3.add(buttonAddAndSub); buttonAd

22、dAndSub.addActionListener(this); panel3.add(buttonDot); buttonDot.addActionListener(this); panel3.add(buttonAdd); buttonAdd.addActionListener(this); panel3.add(buttonEqual); buttonEqual.addActionListener(this); frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE); frame.pack(); frame.show(); /设置各个按钮行

23、为 public void actionPerformed(ActionEvent event) boolean sign = false; /判断是否是double型数参与运算，是为true，不是为false Object temp = event.getSource(); try /如果按下数据按钮，将按下的按钮代表的数据插入的当前文本框字符串之后 for (int i = 0; i = 9; i+) if (temp = buttoni & clickable = true) textAnswer.setText(textAnswer.getText() + Integer.toStri

24、ng(i); /按下.按钮时，判断当前文本框内字符串中含不含.，如果已含，则不允许再插入. if (temp = buttonDot & clickable = true) boolean isDot = false; if (textAnswer.getText().length() = 0) isDot = true; for (int i = 0; i textAnswer.getText().length(); i+) if (. = textAnswer.getText().charAt(i) isDot = true; break; if (isDot = false) textA

25、nswer.setText(textAnswer.getText() + .); if ( (temp = buttonAdd | temp = buttonSub | temp = buttonMul | temp = buttonDiv) & clickable = true) /+操作 if (temp = buttonAdd) switch (prekey) case 0: answerd += Double.parseDouble(textAnswer.getText(); break; case 1: answerd -= Double.parseDouble(textAnswer

26、.getText(); break; case 2: answerd *= Double.parseDouble(textAnswer.getText(); break; case 3: if (Double.parseDouble(textAnswer.getText() = 0) textAnswer.setText(除数不能为零); clickable = false; else answerd /= Double.parseDouble(textAnswer.getText(); break; default: answerd = Double.parseDouble(textAnsw

27、er.getText(); textAnswer.setText(); prekey = key = 0; /-操作 if (temp = buttonSub) switch (prekey) case 0: answerd += Double.parseDouble(textAnswer.getText(); break; case 1: answerd -= Double.parseDouble(textAnswer.getText(); break; case 2: answerd *= Double.parseDouble(textAnswer.getText(); break; ca

28、se 3: if (Double.parseDouble(textAnswer.getText() = 0) textAnswer.setText(除数不能为零); clickable = false; else answerd /= Double.parseDouble(textAnswer.getText(); break; default: answerd = Double.parseDouble(textAnswer.getText(); textAnswer.setText(); prekey = key = 1; /*操作 if (temp = buttonMul) switch

29、(prekey) case 0: answerd += Double.parseDouble(textAnswer.getText(); break; case 1: answerd -= Double.parseDouble(textAnswer.getText(); break; case 2: answerd *= Double.parseDouble(textAnswer.getText(); break; case 3: if (Double.parseDouble(textAnswer.getText() = 0) textAnswer.setText(除数不能为零); click

30、able = false; else answerd /= Double.parseDouble(textAnswer.getText(); break; default: answerd = Double.parseDouble(textAnswer.getText(); textAnswer.setText(); prekey = key = 2; /操作 if (temp = buttonDiv) switch (prekey) case 0: answerd += Double.parseDouble(textAnswer.getText(); break; case 1: answe

31、rd -= Double.parseDouble(textAnswer.getText(); break; case 2: answerd *= Double.parseDouble(textAnswer.getText(); break; case 3: if (Double.parseDouble(textAnswer.getText() = 0) textAnswer.setText(除数不能为零); clickable = false; else answerd /= Double.parseDouble(textAnswer.getText(); break; default: an

32、swerd = Double.parseDouble(textAnswer.getText(); textAnswer.setText(); prekey = key = 3; /=操作 if (temp = buttonEqual & clickable = true) /如果连续按=,则进行连续运算 if (prekey = 5) if (key = 0) answerd += vard; textAnswer.setText(df.format(answerd); if (key = 1) answerd -= vard; textAnswer.setText(df.format(ans

33、werd); if (key = 2) answerd *= vard; textAnswer.setText(df.format(answerd); if (key = 3) if (Double.parseDouble(textAnswer.getText() = 0) textAnswer.setText(除数不能为零); clickable = false; else answerd /= vard; textAnswer.setText(df.format(answerd); else vard = Double.parseDouble(textAnswer.getText(); i

34、f (key = 0) prekey = -1; answerd += Double.parseDouble(textAnswer.getText(); textAnswer.setText(df.format(answerd); if (key = 1) prekey = -1; answerd -= Double.parseDouble(textAnswer.getText(); textAnswer.setText(df.format(answerd); if (key = 2) prekey = -1; answerd *= Double.parseDouble(textAnswer.

35、getText(); textAnswer.setText(df.format(answerd); if (key = 3) prekey = -1; if (Double.parseDouble(textAnswer.getText() = 0) textAnswer.setText(除数不能为零); clickable = false; else answerd /= Double.parseDouble(textAnswer.getText(); textAnswer.setText(df.format(answerd); prekey = 5; /%操作，对第二个操作数除以100 if

36、 (temp = buttonMod & clickable = true) if (answerd = 0) String s = textAnswer.getText(); textAnswer.setText(s); else boolean isDot = false; for (int i = 0; i textAnswer.getText().length(); i+) if (. = textAnswer.getText().charAt(i) isDot = true; break; /如果是double数，除100 if (isDot = true) double dtemp

37、 = Double.parseDouble(textAnswer.getText(); dtemp = dtemp / 100.0; textAnswer.setText(Double.toString(dtemp); else /如果是int数但能被100整除，则去掉末尾两个零 if (Integer.parseInt(textAnswer.getText() % 100 = 0) int itemp = Integer.parseInt(textAnswer.getText(); itemp /= 100; textAnswer.setText(Integer.toString(itemp

38、); /如果是int数，但不能被100整除，则按double数处理 else double dtemp = Double.parseDouble(textAnswer.getText(); dtemp = dtemp / 100.0; textAnswer.setText(Double.toString(dtemp); /开根号运算 if (temp = buttonSqrt & clickable = true) String s = textAnswer.getText(); if (s.charAt(0) = -) textAnswer.setText(负数不能开根号); clickab

39、le = false; else textAnswer.setText(Double.toString(java.lang.Math.sqrt(Double. parseDouble(textAnswer.getText(); /倒数运算 if (temp = buttonDao & clickable = true) if (textAnswer.getText().charAt(0) = 0 & textAnswer.getText().length() = 1) textAnswer.setText(零不能求倒数); clickable = false; else boolean isD

40、ec = true; int i, j, k; String s = Double.toString(1 / Double.parseDouble(textAnswer.getText(); for (i = 0; i s.length(); i+) if (s.charAt(i) = .) break; for (j = i + 1; j s.length(); j+) if (s.charAt(j) != 0) isDec = false; break; if (isDec = true) String stemp = ; for (k = 0; k i; k+) stemp += s.c

41、harAt(k); textAnswer.setText(stemp); else textAnswer.setText(s); /按下+/-按钮时处理 if (temp = buttonAddAndSub & clickable = true) boolean isNumber = true; String s = textAnswer.getText(); for (int i = 0; i = 0 & s.charAt(i) = 9 | s.charAt(i) = . | s.charAt(i) = -) isNumber = false; break; if (isNumber = t

42、rue) /如果当前字符串首字母有-号,代表现在是个负数,再按下时,则将首符号去掉 if (s.charAt(0) = -) textAnswer.setText(); for (int i = 1; i s.length(); i+) char a = s.charAt(i); textAnswer.setText(textAnswer.getText() + a); /如果当前字符串第一个字符不是符号，则添加一个符号在首字母处 else textAnswer.setText(- + s); /计算器有关内存操作 /MC的操作，将内存清0 if (temp = buttonMC & clic

43、kable = true) memoryd = memoryi = 0; textMemory.setText(); /MS的操作，将当前文本框内容保存入内存，显示M if (temp = buttonMS & clickable = true) boolean isDot = false; textMemory.setText( M); for (int i = 0; i textAnswer.getText().length(); i+) if (. = textAnswer.getText().charAt(i) isDot = true; break; /如果是double,则存入memoryd(double存储器) if (isDot = true) memoryd = Double.parseDouble(textAnswer.getText(); memoryi = 0; /保证存储器中存放最新的值 /如果是int,则存入memoryi(int存储器) el