1、第一阶段目标：重构四则运算-- 能把计算的功能封装起来，通过API 接口调用计算方法。
定义一个计算核心类：把四则运算的计算功能包装在一个模块中 (这个模块可以是一个类 Class, 一个DLL等等)。
2、 第二阶段目标 - 通过测试程序和API 接口测试其简单的加减乘除功能。并能看到代码覆盖率。
3、第三阶段目标 – 定义异常处理。
如果输入是有错误的，例如 “1 ++ 2”， 在数值范围是 -1000 .. 1000 的时候，传进去 “10000 + 32768 * 3”, 或者是 “ 248.04 / 0” 怎么办? 怎么告诉函数的调用者 “你错了”? 把返回的字符串定义为 “-1” 来表示？ 那么如果真的计算结果是 “-1” 又怎么处理呢?建议这个时候，要定义各种异常 (Exception)， 让 Core 在碰到各种异常情况的时候，能告诉调用者 - 你错了！
import java.awt.BorderLayout;import java.awt.EventQueue;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.Font;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JLabel;import javax.swing.JPanel;import javax.swing.JTextField;import javax.swing.SwingConstants; import szys.frame; import java.awt.EventQueue; public class frame { private JFrame frame; private JTextField textField; private JTextField textField_1; private JTextField textField_2; private JTextField textField_3; private JTextField textField_4; private JTextField textField_5; frame f; int a; int b; char []op={'+','-','*','/'}; String Sa; String Sb; int result; static int i = (int) (Math.random() * 3); Expression expression = new Expression(); private JButton btnNewButton_1; /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { frame window = new frame(); window.frame.setVisible(true);System.out.print(i); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the application. * @throws Yichang */ public frame() throws Yichang { initialize(); } /** * Initialize the contents of the frame. */ private void initialize() throws Yichang{ frame = new JFrame(); frame.setBounds(100, 100, 517, 352); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel panel = new JPanel(); frame.getContentPane().add(panel, BorderLayout.CENTER); panel.setLayout(null); JLabel lblNewLabel = new JLabel("u56DBu5219u8FD0u7B97u56685.2"); lblNewLabel.setFont(new Font("微软雅黑", Font.PLAIN, 30)); lblNewLabel.setBounds(141, 0, 208, 57); panel.add(lblNewLabel); textField = new JTextField(); textField.setHorizontalAlignment(SwingConstants.CENTER); textField.setFont(new Font("微软雅黑", Font.PLAIN, 30)); textField.setBounds(56, 82, 88, 45); panel.add(textField); textField.setColumns(10); textField_1 = new JTextField(); textField_1.setHorizontalAlignment(SwingConstants.CENTER); textField_1.setFont(new Font("微软雅黑", Font.PLAIN, 30)); textField_1.setColumns(10); textField_1.setBounds(220, 82, 88, 45); panel.add(textField_1); textField_2 = new JTextField("="); textField_2.setHorizontalAlignment(SwingConstants.CENTER); textField_2.setEditable(false); textField_2.setFont(new Font("微软雅黑", Font.PLAIN, 30)); textField_2.setColumns(10); textField_2.setBounds(318, 82, 36, 45); panel.add(textField_2); textField_3 = new JTextField(); textField_3.setHorizontalAlignment(SwingConstants.CENTER); textField_3.setFont(new Font("微软雅黑", Font.PLAIN, 30)); textField_3.setColumns(10); textField_3.setBounds(371, 82, 88, 45); panel.add(textField_3); JButton btnNewButton = new JButton("u505Au5B8Cu4E86"); btnNewButton.setFont(new Font("微软雅黑", Font.PLAIN, 30)); btnNewButton.setBounds(188, 156, 131, 45); panel.add(btnNewButton); JLabel lblNewLabel_1 = new JLabel("u8BA1u7B97u7ED3u679C"); lblNewLabel_1.setFont(new Font("微软雅黑", Font.PLAIN, 30)); lblNewLabel_1.setBounds(56, 222, 131, 35); panel.add(lblNewLabel_1); textField_4 = new JTextField(); textField_4.setFont(new Font("微软雅黑", Font.PLAIN, 20)); textField_4.setColumns(10); textField_4.setBounds(188, 222, 161, 35); panel.add(textField_4); textField_5 = new JTextField(); textField_5.setHorizontalAlignment(SwingConstants.CENTER); textField_5.setEditable(false); textField_5.setFont(new Font("微软雅黑", Font.PLAIN, 30)); textField_5.setText(String.valueOf(op[i])); textField_5.setColumns(10); textField_5.setBounds(159, 82, 44, 45); panel.add(textField_5); a = expression.geta(); Sa = String.valueOf(a); textField.setText(Sa); b = expression.getb(); Sb = String.valueOf(b); textField_1.setText(Sb); btnNewButton_1 = new JButton("u518Du6765 "); btnNewButton_1.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { try { f = new frame(); } catch (Yichang e1) { // TODO 自动生成的 catch 块 e1.printStackTrace(); } frame.dispose(); f.frame.setVisible(true); } }); btnNewButton_1.setFont(new Font("微软雅黑", Font.PLAIN, 30)); btnNewButton_1.setBounds(366, 222, 107, 36); panel.add(btnNewButton_1); btnNewButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0){ int n3=Integer.valueOf(textField_3.getText().toString()); switch(op[i]) { case '+':result = expression.expressionadd();break; case '-':result = expression.expressionmin();break; case '*':result = expression.expressionchen();break; case '/':result = expression.expressionchu();break; } if(textField_3.getText()!="") { if(result==n3) { textField_4.setText(" 正确"); } else { textField_4.setText(" 错误!答案为"+result); } } try { if(textField_3.getText()=="") throw new Yichang("不能为空！"); } catch (Yichang e) { // TODO 自动生成的 catch 块 e.printStackTrace(); } /*try { if(n3<0) throw new Yichang("不可能是负数!"); } catch (Yichang e) { // TODO 自动生成的 catch 块 e.printStackTrace(); }*/ } }); } }
import java.util.*; public class Input { public int a; static Scanner in=new Scanner(System.in); public void seta(int intput){ a = intput; } public Input() { try{ a = in.nextInt(); } catch(InputMismatchException e) { System.err.println(" 错误！ 请你输入一个整数! "); } } public int getinput() { return a; } } Yichang.java: class Yichang extends Exception { public Yichang(String msg) { super(msg); } }
import java.util.*; import szys.Input;public class Expression { private int a = (int)(Math.random() * Math.pow(10,2)-1); private int b = (int)(Math.random() * Math.pow(10,2)-1); private int op; static int c;//用户答案 int answer;//答案 int answer1; static Scanner in=new Scanner(System.in); public int geta() { return a; } public void seta(int a) { this.a = a; } public int getb() { return b; } public void setb(int b) { this.b = b; } public int expressionadd() { answer = a+b; return answer; }public int expressionmin() { answer = a-b; return answer; }public int expressionchen() { answer = a*b; return answer; }public int expressionchu() { b = (b == 0 ? b = 1 +(int)(Math.random() * Math.pow(10,2)-1):b);//排除除法被除数为0的情况 answer = a/b; return answer; }public static void main(String[] args){ int answer; Expression expression = new Expression(); //answer = expression.answer; //Input input = new Input(); //Expression.c = input.a; /*try{ Expression.c = in.nextInt(); } catch(InputMismatchException e) { System.err.println(" 错误！ ,请你输入一个整数"); }*/ //if(answer==c) /* { System.out.print("答对了"); } else System.out.print("答错了");*/ //System.out.print("answer="+answer);} }
class Yichang extends Exception { public Yichang(String msg) { super(msg); } }
运行截图：
