calculator.java

Java案例开发集锦,里面提供了很好的学习例子

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DecimalFormat;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Calculator 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;

    //构造函数
    public Calculator() {
        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();
        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(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.show();
    }

    //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="aa";
                            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: