calculator.java

一个简单的计算器

import java.awt.*;
import java.lang.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.text.DecimalFormat;
public class Calculator implements ActionListener { 
  //private 类型变量
  private JFrame frame;
  private JTextField textAnswer;
  private JPanel panel, panel1, panel2, panel3;
  private JMenuBar mainMenu;
  private JButton buttonBk, buttonCe;
  private JButton buttonC;
  private JButton button[];
  private JButton dot, Add_Sub, Add, Subtract, Mul,  Div, Mod;
  private JButton buttonSqrt, buttonDao, buttonEqual;
  private JMenu helpMenu;
  private JMenuItem topHelp, aboutCal,empty;
  private DecimalFormat Precision; //数据输出精度
  private boolean clickable; //当前能否按键
  private double vard, answerd; //保存double型数据的中间值(vard)和最后结果(answerd)
  private 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
  private JTextArea help; //帮助
  private JScrollPane scrollHelp;
  //构造器
  public Calculator() {
    clickable = true;
    answerd = 0;
    frame = new JFrame("计算器");
    Precision = 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.setHorizontalAlignment(SwingConstants.RIGHT);
    textAnswer.setBackground(new Color(235,235,235));
    panel = new JPanel();
    frame.getContentPane().add(panel);
    panel1 = new JPanel();
    panel2 = new JPanel();
    panel.setLayout(new BorderLayout());
    //设计整个面板
    mainMenu = new JMenuBar();
    helpMenu = new JMenu("帮助(H)");
    topHelp = new JMenuItem("   帮助(H)");
    topHelp.addActionListener(this);
    help = new JTextArea(5, 20);
    scrollHelp = new JScrollPane(help);
    help.setEditable(false);
    help.append("如果你还不会用计算器\n");
    help.append("1.  你一头撞死\n");
    help.append("2.  跳楼去死\n");
    help.append("3.  随便选一个吧！\n");
    //aboutCal = new JMenuItem("   关于(A)");
    helpMenu.add(topHelp);
	aboutCal = new JMenuItem("关于(A)");
    aboutCal.addActionListener(this);
	empty=new JMenu("                            　　　　");
    //helpMenu.add(aboutCal);
    mainMenu.add(helpMenu);
	mainMenu.add(aboutCal);
	mainMenu.add(empty);
    panel.add(mainMenu, BorderLayout.NORTH);
    panel.add(textAnswer, BorderLayout.CENTER);
    panel.add(panel1, BorderLayout.SOUTH);
    panel1.setLayout(new BorderLayout());
    buttonBk = new JButton("Backspace");
    buttonBk.setForeground(new Color(255, 0, 255));
    buttonCe = new JButton("CE");
    buttonCe.setForeground(new Color(255, 0, 255));
    buttonBk.addActionListener(this);
    buttonCe.addActionListener(this);
    panel1.add(panel2, BorderLayout.NORTH);
    panel2.setLayout(new FlowLayout(FlowLayout.RIGHT));
    panel2.add(buttonBk);
    panel2.add(buttonCe);
    panel3 = new JPanel();
    panel1.add(panel3, BorderLayout.CENTER);
    button = new JButton[10];
    for (int i = 0; i < button.length; i++) {
      button[i] = new JButton(Integer.toString(i));
      button[i].setForeground(new Color(0, 0, 255));
    }
    dot = new JButton(".");
    dot.setForeground(new Color(0, 0, 255));
    Add_Sub = new JButton("+/-");
    Add_Sub.setForeground(new Color(0, 0, 255));
    Div = new JButton("/");
    Div.setForeground(new Color(255, 0, 0));
    Mul = new JButton("*");
    Mul.setForeground(new Color(255, 0, 0));
    Subtract = new JButton("-");
    Subtract.setForeground(new Color(255, 0, 0));
	Add = new JButton("+");
    Add.setForeground(new Color(255, 0, 0));
    Mod = new JButton("%");
    Mod.setForeground(new Color(0, 255, 255));
    buttonSqrt = new JButton("sqrt");
    buttonSqrt.setForeground(new Color(0, 255, 255));
    buttonDao = new JButton("1/x");
    buttonDao.setForeground(new Color(0, 255, 255));
    buttonEqual = new JButton("=");
    buttonEqual.setForeground(new Color(255, 0, 0));
    //将所有行为与监听绑定
    panel3.setLayout(new GridLayout(4, 6));
    panel3.add(button[7]);
    button[7].addActionListener(this);
    panel3.add(button[8]);
    button[8].addActionListener(this);
    panel3.add(button[9]);
    button[9].addActionListener(this);
    panel3.add(Add);
    Div.addActionListener(this);
    panel3.add(buttonSqrt);
    buttonSqrt.addActionListener(this);
    panel3.add(button[4]);
    button[4].addActionListener(this);
    panel3.add(button[5]);
    button[5].addActionListener(this);
    panel3.add(button[6]);
    button[6].addActionListener(this);
    panel3.add(Subtract);
    Mul.addActionListener(this);
    panel3.add(buttonDao);
    Mod.addActionListener(this);
    panel3.add(button[1]);
    button[1].addActionListener(this);
    panel3.add(button[2]);
    button[2].addActionListener(this);
    panel3.add(button[3]);
    button[3].addActionListener(this);
    panel3.add(Mul);
    Subtract.addActionListener(this);
    panel3.add(Mod);
    buttonDao.addActionListener(this);
    panel3.add(button[0]);
    button[0].addActionListener(this);
    panel3.add(Add_Sub);
    Add_Sub.addActionListener(this);
    panel3.add(dot);
    dot.addActionListener(this);
    panel3.add(Div);
    Add.addActionListener(this);
    panel3.add(buttonEqual);
    buttonEqual.addActionListener(this);
    frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
    frame.pack();
    frame.show();
  }
  private double AddUp(short prekey) {
	  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;
            case 3:
              if (Double.parseDouble(textAnswer.getText()) == 0) {
				JOptionPane.showMessageDialog(new JFrame(),"傻蛋！\n除数不能为零！！");
                clickable = false;
              }
              else
                answerd /= Double.parseDouble(textAnswer.getText());
              break;
            default:
              answerd = Double.parseDouble(textAnswer.getText());
	  }
	  return answerd;
  }
  //设置各个按钮行为
  public void actionPerformed(ActionEvent event) {
    boolean sign = 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 == button[i] && clickable == true)
          textAnswer.setText(textAnswer.getText() + Integer.toString(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 == dot && 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)
          textAnswer.setText(textAnswer.getText() + ".");
      }
      if ( (temp == Add || temp == Subtract || temp == Mul ||
            temp == Div) && clickable == true) {
        //'+'操作
        if (temp == Add) {
          AddUp(prekey);
		  textAnswer.setText("");
          prekey = key = 0;
        }
        //'-'操作
        if (temp == Subtract) {
          AddUp(prekey);
          textAnswer.setText("");
          prekey = key = 1;
        }
        //'*'操作
        if (temp == Mul) {
          AddUp(prekey);
          textAnswer.setText("");
          prekey = key = 2;
        }
        //'/'操作
        if (temp == Div) {
          AddUp(prekey);
          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(Precision.format(answerd));
          }
          if (key == 1) {
            answerd -= vard;
            textAnswer.setText(Precision.format(answerd));
          }
          if (key == 2) {
            answerd *= vard;
            textAnswer.setText(Precision.format(answerd));
          }
          if (key == 3) {
            if (Double.parseDouble(textAnswer.getText()) == 0) {
              JOptionPane.showMessageDialog(new JFrame(),"傻蛋！\n除数不能为零！！");
              clickable = false;
            }
            else {
              answerd /= vard;
              textAnswer.setText(Precision.format(answerd));
            }
          }
        }
        else {
          vard = Double.parseDouble(textAnswer.getText());
          if (key == 0) {
            prekey = -1;
            answerd += Double.parseDouble(textAnswer.getText());
            textAnswer.setText(Precision.format(answerd));
          }
          if (key == 1) {
            prekey = -1;
            answerd -= Double.parseDouble(textAnswer.getText());
            textAnswer.setText(Precision.format(answerd));
          }
          if (key == 2) {
            prekey = -1;
            answerd *= Double.parseDouble(textAnswer.getText());
            textAnswer.setText(Precision.format(answerd));
          }
          if (key == 3) {
            prekey = -1;
            if (Double.parseDouble(textAnswer.getText()) == 0) {
              JOptionPane.showMessageDialog(new JFrame(),"傻蛋！\n除数不能为零！！");
              clickable = false;
            }
            else {
              answerd /= Double.parseDouble(textAnswer.getText());
              textAnswer.setText(Precision.format(answerd));
            }
          }
        }
        prekey = 5;
      }
      //'%'操作，对第二个操作数除以100
      if (temp == Mod && 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 = 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));
            }
            //否则按double数处理
            else {
              double dtemp = Double.parseDouble(textAnswer.getText());
              dtemp = dtemp / 100.0;
              textAnswer.setText(Double.toString(dtemp));
            }
          }
        }
      }
      //开根号
      if (temp == buttonSqrt && clickable == true) {
        String s = textAnswer.getText();
        if (s.charAt(0) == '-') {
			JOptionPane.showMessageDialog(new JFrame(),"傻蛋！\n负数能开根号吗？\n笨得可以了！！！");
          clickable = false;
        }
        else
          textAnswer.setText(Double.toString(java.lang.Math.sqrt(Double.
              parseDouble(textAnswer.getText()))));
      }
      //倒数
      if (temp == buttonDao && clickable == true) {
        if (textAnswer.getText().charAt(0) == '0' &&
            textAnswer.getText().length() == 1) {
			JOptionPane.showMessageDialog(new JFrame(),"傻蛋！\n零可以求倒数吗？\n笨得可以了！！！");
          clickable = false;
        }
        else {
          boolean isDec = 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.charAt(k);
            textAnswer.setText(stemp);
          }
          else
            textAnswer.setText(s);
        }
      }
      //按下'+/-'按钮时处理
      if (temp == Add_Sub && clickable == true) {
        boolean isNumber = true;
        String s = textAnswer.getText();
        for (int i = 0; i < s.length(); i++)
          if (! (s.charAt(i) >= '0' && s.charAt(i) <= '9' || s.charAt(i) == '.' ||
                 s.charAt(i) == '-')) {
            isNumber = false;
            break;
          }
        if (isNumber == true) {
          //如果当前字符串首字母有'-'号,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);
            }
          }
          else
            textAnswer.setText('-' + s);
        }
      }
      //按下'Backspace'键，将当前字符串中的最后一个字母删除
      if (temp == buttonBk && clickable == true) {
        String s = textAnswer.getText();
        textAnswer.setText("");
        for (int i = 0; i < s.length() - 1; i++) {
          char a = s.charAt(i);
          textAnswer.setText(textAnswer.getText() + a);
        }
      }
      //按下'CE'按钮，将当前文本框内数据清除,同时vard,answer清0
      if (temp == buttonCe) {
        textAnswer.setText("");
        clickable = true;
		vard=answerd=0;
      }
      //按下'帮助'菜单栏
      if (temp == topHelp) {
        JOptionPane.showMessageDialog(panel, scrollHelp);
      }
      //按下'关于'菜单栏
      if (temp == aboutCal) {
        JOptionPane.showMessageDialog(panel, "计算器:1.0版\n开发者:邱小路");
      }
    }
    //输入中如果有操作非法，捕获异常
    catch (Exception e) {
      JOptionPane.showMessageDialog(new JFrame(),"fool!！\noperation is Error!");
      clickable = false;
    }
  }

  public static void main(String args[]) {
    new Calculator();
  }
}