calculator.java

简单的java计算器程序

import java.awt.*;
import java.lang.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.event.*;
import java.text.DecimalFormat;
public class Calculator  extends JFrame 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, buttonMS, 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
  boolean 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;
 
  public  Calculator()            //构造函数
	{ 
			clickable = true;
			answerd = 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();
			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");
			pasteItem.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);
			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(mainMenu, 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 = 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.addActionListener(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 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));
				}
			buttonMC = new JButton("MC");
			buttonMC.setForeground(new Color(255, 0, 0));
			buttonMR = new JButton("MR");
			buttonMR.setForeground(new Color(255, 0, 0));
			buttonMS = new JButton("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 = 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 = new 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));
			//将所有行为与监听绑定
			panel3.setLayout(new GridLayout(4, 6));
			panel3.add(buttonMC);
			buttonMC.addActionListener(this);
			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(buttonDiv);
			buttonDiv.addActionListener(this);
			panel3.add(buttonSqrt);
			buttonSqrt.addActionListener(this);
			panel3.add(buttonMR);
			buttonMR.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(buttonMul);
			buttonMul.addActionListener(this);
			panel3.add(buttonMod);
			buttonMod.addActionListener(this);
			panel3.add(buttonMS);
			buttonMS.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(buttonSub);
			buttonSub.addActionListener(this);
			panel3.add(buttonDao);
			buttonDao.addActionListener(this);
			panel3.add(buttonMAdd);
			buttonMAdd.addActionListener(this);
			panel3.add(button[0]);
			button[0].addActionListener(this);
			panel3.add(buttonAddAndSub);
			buttonAddAndSub.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.setVisible(true);  
  }

  //主函数
  public static void main(String args[])
	  {
		 new Calculator();
		}
  //设置各个按钮行为
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 == 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 == 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)
								textAnswer.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.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(textAnswer.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;
									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(textAnswer.getText());
								}
								 textAnswer.setText("");
								prekey = key = 1;
							}
						 //'*'操作
						 if (temp == buttonMul) 
							 {
								  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) 
														{
															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 = 2;
								}
								 //'/'操作
								 if (temp == buttonDiv)
									 {
											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)
														{
															textAnswer.setText("除数不能为零");
															clickable = false;