Program：设计实现一个小学生数学考试系统，完成随机出题（简单的四则运算），学生答题，自动判分的功能。
Description：代码如下：
1 /*
2 * Description:面向考试系统建立类TestSystem
3 *
4 * */
5
6 package entity;
7
8 public class TestSystem {
9
10 private int num1; //声明两个操作数
11 private int num2;
12 private String operateEle; //声明操作符
13 private static int grade = 0; //记录最后得分
14
15 //定义无参构造方法
16 public TestSystem() {
17
18 }
19
20 //定义带参数的构造方法
21 public TestSystem(int num1,int num2,String operateEle) {
22
23 this.num1 = num1;
24 this.num2 = num2;
25 this.operateEle = operateEle;
26 }
27
28 //设置setter()和getter()方法
29 public int getNum1() {
30 return num1;
31 }
32
33 public void setNum1(int num1) {
34 this.num1 = num1;
35 }
36
37 public int getNum2() {
38 return num2;
39 }
40
41 public void setNum2(int num2) {
42 this.num2 = num2;
43 }
44
45 //覆写toString()方法
46 public String toString() {
47
48 return this.num1 + this.operateEle + this.num2;
49 }
50
51 //取得表达式的正确结果
52 public int getResult() {
53
54 int result = 0;
55 switch(this.operateEle) {
56
57 case "+": result = this.num1 + this.num2;break;
58
59 case "-": result = this.num1 - this.num2;break;
60
61 case "*": result = this.num1 * this.num2;break;
62
63 case "/": result = this.num1 / this.num2;break;
64 }
65
66 return result;
67 }
68
69 //向屏幕输出总成绩
70 public static void getGrade() {
71
72 System.out.println( "考试结束，最后成绩为：" + TestSystem.grade );
73 }
74
75 //答对问题，将对应的成绩加入总成绩
76 public static void setGrade(int grade) {
77
78 TestSystem.grade += grade;
79 }
80
81 //将总成绩清零
82 public static void clear() {
83
84 TestSystem.grade = 0;
85 }
86
87
88 }
1 /*
2 * Description:定义类Operate,用于获取随机操作数和操作符
3 *
4 * */
5
6
7 package tools;
8
9 import java.util.Random;
10 import java.util.Scanner;
11
12 public class Operate {
13
14 //定义方法，返回一个100以内的随机数
15 public static int getRandom() {
16
17 Random ran = new Random();
18
19 return ran.nextInt(100);
20 }
21
22 //定义方法，返回操作符
23 public static String getOperateEle() {
24
25 String[] operateEle = {"+","-","*","/"};
26 Random ran = new Random();
27
28 return operateEle[ran.nextInt(4)];
29 }
30
31
32 //定义方法，取得用户输入的结果
33 public static int getInput() {
34
35 Scanner scan = new Scanner(System.in); //实例化Scanner对象
36 int result = 0;
37
38 System.out.println( "请输入结果：" );
39 result = scan.nextInt();
40 return result;
41
42 }
43
44
45 }
1 /*
2 * Description:小学简单四则运算，系统随即出题，每题20分
3 *
4 * Written By:Cai
5 *
6 * Date Written:2017-09-25
7 *
8 * */
9
10 package main;
11
12 import tools.Operate; //导入自定义的两个类
13 import entity.TestSystem;
14
15 public class DemoTwo4 {
16
17 public static void main(String args[]) {
18
19 int i = 0; //记录答题个数
20 int inputResult = 0; //接收用户输入的结果
21 do {
22 //实例化TestSystem类型对象
23 TestSystem ts = new TestSystem(Operate.getRandom(),Operate.getRandom(),Operate.getOperateEle());
24 System.out.println(ts); //输出表达式
25 inputResult = Operate.getInput(); //用户输入
26 if( inputResult == ts.getResult() ) { //回答正确，加上对应的分值分
27
28 System.out.println( "回答正确!" );
29 TestSystem.setGrade(20);
30 }else { //回答错误
31
32 System.out.println( "回答错误！" );
33 }
34 i++;
35
36 }while(i < 5); //一共五道题（方便验证）
37
38 TestSystem.getGrade(); //打印最后结果
39 TestSystem.clear(); //总成绩清零
40
41 }
42 }