阶段1： 1、定义主界面菜单， 1、参数设置 2、小学二年级口算题 3、小学三年级口算题 4、小学四年级口算题 5、错题集 其中参数设置包括出题个数（缺省值为30）、操作数数值范围。 小学二年级口算题操作数为两个、可进行加减乘除运算（除法必须可以整除），操作数范围不超过100. 小学三年级口算题操作数不超过4个，可以进行加减乘除，操作数范围不超过1000.（要求采用继承小学二年级出题类的方式，实现小学三年级的出题类） 小学四年级口算题操作数不超过5个，可以进行加减乘除，还可以加入括号运算。 （要求采用继承小学三年级出题类的方式，实现小学四年级的出题类）
阶段2： 1、学生实时答题结束后，可以选择是否进行下一套题目答题，如果选择是，则抽取下一套题进行答题，答题结束可以通过查看错题本，查询今日做题正确率。 2、也可以针对错题进行二次答题。
(一)主函数,菜单实现
1 package Math_06;
2
3 import java.util.Scanner;
4
5 public class Main {
6 static int num;
7 static int fw;
8 static Scanner sc = new Scanner(System.in);
9 public static void main (String [] args)
10 {
11
12 while(true) {
13 System.out.println("1、参数设置");
14 System.out.println("2、小学二年级口算题");
15 System.out.println("3、小学三年级口算题");
16 System.out.println("4、小学四年级口算题");
17 System.out.println("5、错题集");
18
19 int str = sc.nextInt();
20 switch(str) {
21 case 1 -> Setnumber();
22 case 2 -> student_02( );
23 case 3 -> student_03();
24 case 4 -> student_04();
25 case 5 -> Wrong();
26 default -> System.out.println("输入错误");
27 }
28 }
29 }
30 public static void Setnumber()
31 {
32 System.out.println("请输入出题个数");
33 num = sc.nextInt();
34 System.out.println("请输入出题范围");
35 fw = sc.nextInt();
36 }
37 public static void student_02()
38 {
39 Student_02 s = new Student_02(num , fw);
40 s.init(num, fw);
41 s.show( num);
42
43 System.out.println("是否进入错题集 : 是1 否2");
44 int j= sc.nextInt();
45
46 if(j == 1)
47 {
48 s.showben();
49 }
50 }
51 public static void student_03()
52 {
53 Student_03 s = new Student_03(num , fw);
54 s.init(num, fw);
55 s.show_rate( );
56
57 System.out.println("是否进入错题集 : 是1 否2");
58 int j= sc.nextInt();
59 if(j == 1)
60 {
61 s.showben();
62 }
63 }
64 public static void student_04()
65 {
66 Student_04 s = new Student_04(num , fw);
67 s.init(num , fw);
68 System.out.println("是否进入错题集 : 是1 否2");
69 int j= sc.nextInt();
70
71 if(j == 1)
72 {
73 s.showben();
74 }
75 }
76 public static void Wrong()
77 {
78
79 }
80 }
(二)二年级 : 两个操作数
1 package Math_06;
2
3 import java.util.Random;
4 import java.util.Scanner;
5
6 public class Student_02 {
7
8 private int num = 30;
9 private int fw;
10
11 public char[] f = new char[100010];
12 public int [] s1 = new int [100010];
13 public int [] s2 = new int [100010];
14 public int [] answer = new int [100010];
15 public int [] ben = new int [100010];
16 public int y = 0;
17 public int s = 1;
18 Student_02()
19 {
20
21 }
22 Student_02(int num , int fw)
23 {
24 this.setNum(num);
25 this.setFw(fw);
26 }
27
28 public void init(int num , int fw) {
29 int t = 0;
30 Random rm=new Random(); //随机数
31
32 for(int i = 0 ; i < num ; i ++)
33 {
34 t++;
35 //符号
36 int number_3;
37 number_3 = rm.nextInt(4)+1;
38 //数字
39 int number_1 = rm.nextInt(fw);
40 int number_2 = rm.nextInt(fw);
41 s1[t] = number_1 ;
42 s2[t] = number_2 ;
43 if(number_3==1)
44 {
45 f[t] = '+';
46 answer[s++] = number_1 + number_2;
47 }
48 else if(number_3==2)
49 {
50 f[t] = '-';
51 answer[s++] = number_1 - number_2;
52 }
53 else if (number_3==3)
54 {
55 f[t] = '*';
56 answer[s++] = number_1 * number_2;
57 }
58 else if(number_3==4)
59 {
60 f[t] = '/';
61 answer[s++] = number_1 / number_2;
62 }
63 }
64 }
65 public void show( int n) {
66 for(int i = 1 ; i <= n ; i ++) {
67 System.out.print(s1[i]);
68
69 if(f[i] == '+')
70 {
71 System.out.print("+");
72 }
73 else if(f[i] == '-')
74 {
75
76 System.out.print( "-" );
77 }
78 else if (f[i] == '*')
79 {
80
81 System.out.print( "*" );
82 }
83 else if(f[i] == '/')
84 {
85
86 System.out.print( "/" );
87 }
88
89 System.out.print(s2[i]);
90 System.out.println( "=\t\t" );
91 Scanner sc = new Scanner(System.in);
92
93 int d = sc.nextInt();
94 if(d != answer[i])
95 {
96 System.out.println( "答案错误" );
97 ben[y++] = i;
98 }
99
100 }
101 System.out.println("错题个数: " + y);
102 int b = (n-y)*10/n*10;
103 int d = b + (n-y)*10%n*10/n;
104 System.out.println("正确率: " + d + "%" );
105 }
106 public void showben()
107 {
108 System.out.println("错题本重练系统");
109 for(int i = 0 ; i < y ; i ++) {
110 System.out.print(s1[ben[i]]);
111
112 if(f[ben[i]] == '+')
113 {
114 System.out.print("+");
115 }
116 else if(f[ben[i]] == '-')
117 {
118
119 System.out.print( "-" );
120 }
121 else if (f[ben[i]] == '*')
122 {
123
124 System.out.print( "*" );
125 }
126 else if(f[ben[i]] == '/')
127 {
128
129 System.out.print( "/" );
130 }
131
132 System.out.print(s2[ben[i]]);
133 System.out.println( "=\t\t" );
134 Scanner sc = new Scanner(System.in);
135
136 int d = sc.nextInt();
137 if(d != answer[ben[i]])
138 {
139 System.out.println( "答案错误" );
140 }
141 }
142 }
143 public int getNum() {
144 return num;
145 }
146 public void setNum(int num) {
147 this.num = num;
148 }
149 public int getFw() {
150 return fw;
151 }
152 public void setFw(int fw) {
153 this.fw = fw;
154 }
155
156 }
(三)三年级 : 实现4个操作数 (难点 : 4个数的算数优先级运算)
1 package Math_06;
2
3 import java.util.Random;
4 import java.util.Scanner;
5
6 public class Student_03 extends Student_02{
7 public int [] answer_1 = new int [100010];
8 static String []arr = new String[100000];
9 int s = 1;
10 int t = 1;
11
12 Student_03(int num , int fw)
13 {
14 super(num , fw);
15 }
16 @Override
17 public void init(int num , int fw) {
18
19 Random rm=new Random(); //随机数
20
21 for(int i = 0 ; i < num ; i ++)
22 {
23 int num_f = 1;
24 int num_s = 1;
25 //前两个数字 +-*/ 加减不算,乘除算
26 int number_1 = rm.nextInt(fw);
27 int number_2 = rm.nextInt(fw);
28 int number_3;
29 number_3 = rm.nextInt(4)+1;
30
31 String str = "" + number_1;
32
33 if(number_3 == 3)
34 {
35 answer[num_s ] = number_1 * number_2;
36 str += '*';
37 }
38 else if(number_3 == 4)
39 {
40 answer[num_s ] = number_1 / number_2;
41 str += '/';
42 }
43 else
44 {
45 answer[num_s++] = number_1;
46 answer[num_s ] = number_2;
47 if(number_3 == 1)
48 {
49 f[num_f++] = '+';
50 str += '+';
51 }
52 else
53 {
54 f[num_f++] = '-';
55 str += '-';
56 }
57 }
58 str += number_2;
59 //后两个数 , 加减不算,乘除算
60 for(int j = 0 ; j < 2; j++)
61 {
62 number_3 = rm.nextInt(4)+1;
63 int number_4 = rm.nextInt(fw);
64
65 if(number_3 == 3)
66 {
67 answer[num_s ] *= number_4;
68 str += '*';
69 }
70 else if(number_3 == 4)
71 {
72 answer[num_s ] /= number_4;
73 str += '/';
74 }
75 else
76 {
77 answer[++num_s] = number_4;
78 if(number_3 == 1)
79 {
80 f[num_f++] = '+';
81 str += '+';
82 }
83 else
84 {
85 f[num_f++] = '-';
86 str += '-';
87 }
88 }
89 str += number_4;
90 }
91
92 //乘除已算完 , 只剩加减 , 计算最终答案
93 answer_1[s] = answer[1];
94 for(int j = 1 ;j < num_f ; j++)
95 {
96 if(f[j] == '+')
97 answer_1[s] += answer[j+1];
98 else
99 answer_1[s] -= answer[j+1];
100 }
101 show(str , answer_1[s]);
102 s++;
103 }
104 }
105 public void show(String str , int answer ) {
106
107 arr[t] = str;
108
109 System.out.println( arr[t] +"=\t\t" );
110 Scanner sc = new Scanner(System.in);
111
112 int d = sc.nextInt();
113 if(d != answer )
114 {
115 System.out.println( "答案错误" );
116 ben[y++] = t;
117 }
118 t++;
119 }
120 public void show_rate()
121 {
122 System.out.println("错题个数: " + y);
123 int b = (getNum()-y)*10/getNum()*10;
124 int d1 = b + (getNum()-y)*10%getNum()*10/getNum();
125 System.out.println("正确率: " + d1 + "%" );
126 }
127 @Override
128 public void showben()
129 {
130 System.out.println("错题本重练系统");
131 for(int i = 0 ; i < y ; i ++) {
132
133 System.out.println( arr[ ben[i] ] + "=\t\t" );
134 Scanner sc = new Scanner(System.in);
135
136 int d = sc.nextInt();
137 if(d != answer_1[ ben[i] ] )
138 {
139 System.out.println( "答案错误" );
140 }
141 }
142 }
143
144 }
(四)四年级 : 加括号运算 (难点 : 加入括号后的优先级运算)
1 package Math_06;
2
3 import java.util.Random;
4 import java.util.Scanner;
5
6 public class Student_04 extends Student_03{
7
8 Student_04(int num , int fw)
9 {
10 super(num , fw);
11 }
12 @Override
13 public void init(int num , int fw) {
14
15 Random rm=new Random(); //随机数
16
17 for(int i = 0 ; i < num ; i ++)
18 {
19 int cnt = 0;
20 int flag = 0;
21 int num_f = 1;
22 int num_s = 1;
23 //前两个数字 +-*/ 加减不算,乘除算
24 int number_1 = rm.nextInt(fw)+1;
25 int number_2 = rm.nextInt(fw)+1;
26 int number_3 = rm.nextInt(4)+1;
27 String str = "";
28
29 //前括号
30 if(number_1 % 2 == 0 || number_1 % 3 == 0)
31 {
32 cnt = 1;
33 str = "(" + number_1;
34 }
35 if(cnt == 1) //有括号
36 {
37 if(number_3==1)
38 {
39 str += '+';
40 answer[num_s ] = number_1 + number_2;
41 }
42 else if(number_3==2)
43 {
44 str += '-';
45 answer[num_s ] = number_1 - number_2;
46 }
47 else if (number_3==3)
48 {
49 str += '*';
50 answer[num_s ] = number_1 * number_2;
51 }
52 else if(number_3==4)
53 {
54 str += '/';
55 answer[num_s ] = number_1 / number_2;
56 }
57 str += number_2 + ")";
58 }
59 //没括号
60 else {
61 str += number_1 ;
62 if(number_3 == 3)
63 {
64 answer[num_s ] = number_1 * number_2;
65 str += '*';
66 }
67 else if(number_3 == 4)
68 {
69 answer[num_s ] = number_1 / number_2;
70 str += '/';
71 }
72 else
73 {
74 answer[num_s++] = number_1;
75 answer[num_s ] = number_2;
76 if(number_3 == 1)
77 {
78 f[num_f++] = '+';
79 str += '+';
80 }
81 else
82 {
83 f[num_f++] = '-';
84 str += '-';
85 }
86 }
87 str += number_2;
88 }
89
90 //后括号
91 if( cnt == 0)
92 {
93 flag = 1;
94 }
95 //有括号
96 if(flag == 1)
97 {
98 int number_4 = rm.nextInt(4)+1;
99 number_1 = rm.nextInt(fw);
100 number_2 = rm.nextInt(fw);
101 number_3 = rm.nextInt(4)+1;
102 int fu = 0;
103 if(number_3==1)
104 {
105 fu = 1;
106 answer[++num_s ] = number_1 + number_2;
107 }
108 else if(number_3==2)
109 {
110 fu = 2;
111 answer[++num_s ] = number_1 - number_2;
112 }
113 else if (number_3==3)
114 {
115 fu = 3;
116 answer[++num_s ] = number_1 * number_2;
117 }
118 else if(number_3==4)
119 {
120 fu = 0;
121 answer[++num_s ] = number_1 / number_2;
122 }
123
124 //计算2,3连接处
125 if(number_4 == 3)
126 {
127 answer[--num_s ] *= answer[++num_s ];
128 str += '*';
129 }
130 else if(number_4 == 4)
131 {
132 answer[--num_s ] /= answer[++num_s ];
133 str += '/';
134 }
135 else
136 {
137 if(number_4 == 1)
138 {
139 f[num_f++] = '+';
140 str += '+';
141 }
142 else
143 {
144 f[num_f++] = '-';
145 str += '-';
146 }
147 }
148 str += "(" + number_1;
149 if(fu == 1)
150 str += '+';
151 else if (fu == 2)
152 str += '-';
153 else if(fu == 3)
154 str += '*';
155 else str += '/';
156 str += number_2 + ")";
157 }
158 //无括号
159 else {
160 for(int j = 0 ; j < 2; j++)
161 {
162 number_3 = rm.nextInt(4)+1;
163 int number_4 = rm.nextInt(fw);
164
165 if(number_3 == 3)
166 {
167 answer[num_s ] *= number_4;
168 str += '*';
169 }
170 else if(number_3 == 4)
171 {
172 answer[num_s ] /= number_4;
173 str += '/';
174 }
175 else
176 {
177 answer[++num_s] = number_4;
178 if(number_3 == 1)
179 {
180 f[num_f++] = '+';
181 str += '+';
182 }
183 else
184 {
185 f[num_f++] = '-';
186 str += '-';
187 }
188 }
189 str += number_4;
190 }
191 }
192
193 //乘除已算完 , 只剩加减 , 计算最终答案
194 answer_1[s] = answer[1];
195 for(int j = 1 ;j < num_f ; j++)
196 {
197 if(f[j] == '+')
198 answer_1[s] += answer[j+1];
199 else
200 answer_1[s] -= answer[j+1];
201 }
202 show(str , answer_1[s]);
203 s++;
204 }
205 }
206 public void show(String str , int answer ) {
207
208 arr[t] = str;
209
210 System.out.println( arr[t] +"=\t\t" );
211 Scanner sc = new Scanner(System.in);
212
213 int d = sc.nextInt();
214 if(d != answer )
215 {
216 System.out.println( "答案错误" + answer );
217 ben[y++] = t;
218 }
219 t++;
220 }
221 public void show_rate()
222 {
223 System.out.println("错题个数: " + y);
224 int b = (getNum()-y)*10/getNum()*10;
225 int d1 = b + (getNum()-y)*10%getNum()*10/getNum();
226 System.out.println("正确率: " + d1 + "%" );
227 }
228 @Override
229 public void showben()
230 {
231 System.out.println("错题本重练系统");
232 for(int i = 0 ; i < y ; i ++) {
233
234 System.out.println( arr[ ben[i] ] + "=\t\t" );
235 Scanner sc = new Scanner(System.in);
236
237 int d = sc.nextInt();
238 if(d != answer_1[ ben[i] ] )
239 {
240 System.out.println( "答案错误" );
241 }
242 }
243 }
244 }
标签：str,int,四则运算,number,++,num,测试,answer,课堂 From： https://www.cnblogs.com/fan-wang/p/16754613.html