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云代码 - java代码库

计算器

2017-04-03 作者： baymax举报

[java]代码库

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package gui;
 
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
 
 
public class Calculator2 extends JFrame implements ActionListener{
 
    //显示的名字
    private final String[] KEYS={ "7", "8", "9", "/", "sqrt", "4", "5", "6",
            "*", "%", "1", "2", "3", "-", "1/x", "0", "+/-", ".", "+", "=" };
    private final String[] COMMAND={"Backspace","CE","C"};
    private final String[] M={"","MC" ,"MR","MS","M+"};
    //按钮
    private JButton[] keys=new JButton[KEYS.length];
    private JButton[] command=new JButton[COMMAND.length];
    private JButton[] m=new JButton[M.length];
    //计算结果文本框
    private JTextField resultTxt=new JTextField("0");
     
    //标记用户按的是否是整个表达式的第一个数字，或者是运算符后的第一个数字
    private boolean firstDigit=true;
    //计算中间结果
    private double resultNum=0.0;
    //当前运算的运算符
    private String operator="=";
    //操作是否合法
    private boolean operateValidFlag=true;
     
    /**
     * 构造函数
     * @param args
     */
     
    public Calculator2() {
        // TODO Auto-generated constructor stub
        super();
        //初始化计算器
        init();
        this.setBackground(Color.LIGHT_GRAY);
        this.setTitle("计算器");
        this.setLocation(500, 400);
        //不许修改计算器大小
        this.setResizable(false);
        //是计算器中的各组件大小合适
        this.pack();
    }
    /**
     * 初始化计算器
     */
    private void init() {
        // TODO Auto-generated method stub
        //文本框中内容右对齐
        resultTxt.setHorizontalAlignment(JTextField.RIGHT );
        //不允许修改结果文本框
        resultTxt.setEditable(false);
        //设置文本框背景颜色
        resultTxt.setBackground(Color.white);
         
        /**
         * 初始化计算器上键的按钮，将键放到一个画板内
         */
        JPanel calkeyPanel=new JPanel();
        //用网格布局，4X5 网格之间的水平方向间隔为3个象素，垂直方向间隔为3个象素
        calkeyPanel.setLayout(new GridLayout(4, 5, 3, 3));
        for(int i=0;i<KEYS.length;i++){
            keys[i]=new JButton(KEYS[i]);
            calkeyPanel.add(keys[i]);
            keys[i].setForeground(Color.blue);
        }
         
        //运算符键用红色表示，其他蓝色
        keys[3].setForeground(Color.red);
        keys[8].setForeground(Color.red);
        keys[13].setForeground(Color.red);
        keys[19].setForeground(Color.red);
         
        /**
         * 初始化功能键，用红色表示。将功能键放到一个画板内
         */
        JPanel commandPanel=new JPanel();
        //用网格布局 1X3
        commandPanel.setLayout(new GridLayout(1, 3, 3, 3));
        for(int i=0;i<COMMAND.length;i++){
            command[i]=new JButton(COMMAND[i]);
            commandPanel.add(command[i]);
            command[i].setForeground(Color.red);
        }
        /**
         * 初始化M键，用red表示。将其放到一个面板上
         */
        JPanel mPanel=new JPanel();
        mPanel.setLayout(new GridLayout(5, 1, 3, 3));
        for(int i=0;i<M.length;i++){
            m[i]=new JButton(M[i]);
            mPanel.add(m[i]);
            m[i].setForeground(Color.red);
        }
         
        /**
         * 计算器的整体布局，将calkey和command画板放到计算器的中部
         * 将文本框放到北部，m画板放到西部
         */
        //新建一个大画板
        JPanel panel=new JPanel();
        panel.setLayout(new BorderLayout(3, 3));
        panel.add("North",commandPanel);
        panel.add("Center",calkeyPanel);
         
        //建立一个画板放文本框
        JPanel top=new JPanel();
        top.setLayout(new BorderLayout());
        top.add("Center",resultTxt);
        //整体布局
        getContentPane().setLayout(new BorderLayout(3,5));
        getContentPane().add("North", top);
        getContentPane().add("Center", panel);
        getContentPane().add("West", mPanel);
         
        //为各个按钮添加监听器
        //都使用同一个事件监听，即本对象。
        for(int i=0;i<KEYS.length;i++){
            keys[i].addActionListener(this);
        }
        for(int i=0;i<COMMAND.length;i++){
            command[i].addActionListener(this);
        }
        for(int i=0;i<M.length;i++){
            m[i].addActionListener(this);
        }
    }
 
    /**
     * 处理事件
     * @param args
     */
     
    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        //获取事件源的标签
        String label=e.getActionCommand();
        if(label.equals(COMMAND[0])){
            handleBackspace();
        }else if (label.equals(COMMAND[1])) {
            resultTxt.setText("0");
        }else if (label.equals(COMMAND[2])) {
            handleC();
        }else if ("0123456789.".indexOf(label)>=0) {
            handleNumber(label);
        }else {//用户按了运算符键
            handleOperator(label);
        }
    }
 
 
    private void handleBackspace() {
        // TODO Auto-generated method stub
        String text=resultTxt.getText();
        int i=text.length();
        if(i>0){
            //退格，建文本最后一个字符去掉
            text=text.substring(0, i-1);
            if(text.length()==0){
                //如果文本没有内容，则初始化计算器的各种值r
                resultTxt.setText("0");
                firstDigit=true;
                operator="=";
            }else {
                resultTxt.setText(text);//显示新的文本
            }
        }
    }
    private void handleC() {
        // TODO Auto-generated method stub
        //初始化计算器的各种值
        resultTxt.setText("0");
        firstDigit=true;
        operator="=";
    }
    private void handleNumber(String key) {
        // TODO Auto-generated method stub
        if(firstDigit){
            resultTxt.setText(key);
        }else if ((key.equals("."))&&(resultTxt.getText().indexOf("."))<0) {
            // 输入的是小数点，并且之前没有小数点，则将小数点附在结果文本框的后面
            resultTxt.setText(resultTxt.getText()+".");
        }else if (!key.equals(".")) {
            //如果输入的不是小数点，则将数字附在结果文本框的后面
            resultTxt.setText(resultTxt.getText()+key);
        }
        //以后输入的肯定不的第一个数字了
        firstDigit=false;
    }
    private void handleOperator(String key) {
        // TODO Auto-generated method stub
        if(operator.equals("/")){
            //如果当前结果文本框中的值=0
            if(getNumberFromText()==0.0){
                //操作不合法
                operateValidFlag=false;
                resultTxt.setText("除数不能为零");
            }else {
                resultNum/=getNumberFromText();
            }
        }else if (operator.equals("1/x")) {
            //倒数运算
            if (resultNum==0.0) {
                //操作不合法
                operateValidFlag=false;
                resultTxt.setText("0没有倒数");
            }else {
                resultNum=1/resultNum;
            }
        }else if (operator.equals("+")) {
            resultNum+=getNumberFromText();
        }else if (operator.equals("-")) {
            resultNum-=getNumberFromText();
        }else if (operator.equals("*")) {
            resultNum*=getNumberFromText();
        }else if (operator.equals("sqrt")) {
            resultNum=Math.sqrt(resultNum);
        }else if (operator.equals("%")) {
            resultNum=resultNum/100;
        }else if (operator.equals("+/-")) {
            resultNum=resultNum*(-1);
        }else if (operator.equals("=")) {
            resultNum=getNumberFromText();
        }
         
        if (operateValidFlag) {
            //双精度浮点数的运算
            long t1;
            double t2;
            t1=(long)resultNum;
            t2=resultNum-t1;
            if(t2==0){
                resultTxt.setText(String.valueOf(t1));
            }else {
                resultTxt.setText(String.valueOf(resultNum));
            }
        }
        //运算符等于用户按的按钮
        operator=key;
        firstDigit=true;
        operateValidFlag=true;
         
    }
     
    //从结果文本中获取数字
    private double getNumberFromText() {
        // TODO Auto-generated method stub
        double result=0;
        try {
            result=Double.valueOf(resultTxt.getText()).doubleValue();
        } catch (NumberFormatException e) {
            // TODO: handle exception
        }
        return result;
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
 
        Calculator2 calculator2=new Calculator2();
        calculator2.setVisible(true);
        calculator2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
 
}

[代码运行效果截图]


计算器


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