软件工程第二次作业

时间：2015-04-12 22:36:28 阅读：237 评论：0 收藏：0 [点我收藏+]

代码运行如下：

mport javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class heya1 extends JFrame implements ActionListener
{
    private boolean dotExist, operated, equaled; // 帮助运算的布尔变量
    private double storedNumber; // 目前的结果
    private char lastOperator; // 表示上一运算符
    private JTextField operation; // 结果栏
    private JButton dot, plus, minus, multi, div, sqrt, equal, changePN, clear; // 运算符
    private JButton[] numbers; // 数字

    // 构造者
    public heya1()
    {
        setTitle("Calculator");
        // 初始化变量
        dotExist = false; // 表示当前的数是否有小数点
        operated = false; // 表示任意运算符是否被按下
        equaled = false; // 表示等号是否被按下
        storedNumber = 0;
        lastOperator = ‘?‘;
        // 初始化窗口变量
        operation = new JTextField("0");
        operation.setEditable(false);
        numbers = new JButton[10];
        for (int i = 0; i < 10; i++)
        numbers[i] = new JButton("" + i);
        dot = new JButton(".");
        plus = new JButton("+");
        minus = new JButton("-");
        multi = new JButton("*");
        div = new JButton("/");
        sqrt = new JButton("√");
        equal = new JButton("=");
        changePN = new JButton("±");
        clear = new JButton("AC");
        // 将窗口物体放入窗口
        GridBagLayout layout = new GridBagLayout();
        getContentPane().setLayout(layout);
        addComponent(layout, operation, 0, 0, 4, 1);
        addComponent(layout, numbers[1], 1, 0, 1, 1);
        addComponent(layout, numbers[2], 1, 1, 1, 1);
        addComponent(layout, numbers[3], 1, 2, 1, 1);
        addComponent(layout, numbers[4], 2, 0, 1, 1);
        addComponent(layout, numbers[5], 2, 1, 1, 1);
        addComponent(layout, numbers[6], 2, 2, 1, 1);
        addComponent(layout, numbers[7], 3, 0, 1, 1);
        addComponent(layout, numbers[8], 3, 1, 1, 1);
        addComponent(layout, numbers[9], 3, 2, 1, 1);
        addComponent(layout, dot, 4, 0, 1, 1);
        addComponent(layout, numbers[0], 4, 1, 1, 1);
        addComponent(layout, sqrt, 4, 2, 1, 1);
        addComponent(layout, plus, 1, 3, 1, 1);
        addComponent(layout, minus, 2, 3, 1, 1);
        addComponent(layout, multi, 3, 3, 1, 1);
        addComponent(layout, div, 4, 3, 1, 1);
        addComponent(layout, equal, 5, 0, 2, 1);
        addComponent(layout, changePN, 5, 2, 1, 1);
        addComponent(layout, clear, 5, 3, 1, 1);
    }

    // 对按钮进行反应的方法
    public void actionPerformed(ActionEvent e)
    {
        JButton btn = (JButton)e.getSource();
        if (btn == clear)
        {
            operation.setText("0");
            dotExist = false;
            storedNumber = 0;
            lastOperator = ‘?‘;
        }
        else if (btn == equal)
        {
            operate(‘=‘);
            equaled = true;
        }
        else if (btn == plus)
        {
            operate(‘+‘);
            equaled = false;
        }
        else if (btn == minus)
        {
            operate(‘-‘);
            equaled = false;
        }
        else if (btn == multi)
        {
            operate(‘*‘);
            equaled = false;
        }
        else if (btn == div)
        {
            operate(‘/‘);
            equaled = false;
        }
        else if (btn == changePN)
        {
            operate(‘p‘);
            operate(‘=‘);
            equaled = true;
        }
        else if (btn == sqrt)
        {
            operate(‘s‘);
            operate(‘=‘);
            equaled = true;
        }
        else
        {
            if (equaled)
            storedNumber = 0;
            for (int i = 0; i < 10; i++)
            if (btn == numbers[i])
            {
                if (operation.getText().equals("0"))
                    operation.setText("" + i);
                else if(! operated)
                    operation.setText(operation.getText() + i);
                else
                {
                    operation.setText("" + i);
                    operated = false;
                }
            }
            if (btn == dot && ! dotExist)
            {
                operation.setText(operation.getText() + ".");
                dotExist = true;
            }
        }
    }
    // 进行运算的方法
    private void operate(char operator)
    {
        double currentNumber = Double.valueOf(operation.getText()).doubleValue();
        if (lastOperator == ‘?‘)
        storedNumber = currentNumber;
        else if (lastOperator == ‘+‘)
        storedNumber += currentNumber;
        else if (lastOperator == ‘-‘)
        storedNumber -= currentNumber;
        else if (lastOperator == ‘*‘)
        storedNumber *= currentNumber;
        else if (lastOperator == ‘/‘)
        storedNumber /= currentNumber;
        else if (lastOperator == ‘p‘)
        storedNumber *= -1;
        else if (lastOperator == ‘s‘)
        storedNumber = Math.sqrt(currentNumber);
        else if (lastOperator == ‘=‘ && equaled)
        storedNumber = currentNumber;
        operation.setText("" + storedNumber);
        operated = true;
        lastOperator = operator;
    }

    // 快捷使用GridBagLayout的方法
    private void addComponent(GridBagLayout layout, Component component, int row, int col, int width, int height)
    {
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.fill = GridBagConstraints.BOTH;
        constraints.insets = new Insets(10, 2, 10, 2);
        constraints.weightx = 100;
        constraints.weighty = 100;
        constraints.gridx = col;
        constraints.gridy = row;
        constraints.gridwidth = width;
        constraints.gridheight = height;
        layout.setConstraints(component, constraints);
        if (component instanceof JButton)
        ((JButton)component).addActionListener(this);
        getContentPane().add(component);
    }

    // 主方法初始化并显示窗口
    public static void main(String[] args)
    {
        heya1 calc = new heya1();
        calc.setSize(290, 400);
        calc.setVisible(true);
    }
}