完善课上的口算题卡代码，实现重复题目的检测、题目数字范围、加减乘除算式的参数化等扩展功能，提交代码和运行截图。
import java.util.*;
public class test {
private static String strTest = "";
private static final Random RANDOM = new Random();
private static final Scanner SCANNER = new Scanner(System.in);
private static Integer number_random;
public static void main(String[] args) {
System.out.print("请输入参与数字的最大值：");
number_random = SCANNER.nextInt();
System.out.print("请输入要生成题目数量：");
getExpression(SCANNER.nextInt());
}
/**
* 计算公约数（在下面getExpression方法里面已经排除 0 ）
*/
public static int gcd(int a, int b) {
if (a % b == 0) {
return b;
} else {
return gcd(b, a % b);
}
}
/**
* 获取随机运算符
*/
public static char getOperator() {
char[] signal = {'+', '-', '*', '/'};
return signal[RANDOM.nextInt(4)];
}
/**
* 生成表达式
*/
public static void getExpression(int getNums) {
char operator1, operator2;
int num1, num2, num3;
while (getNums > 0) {
boolean flag = false;
getNums--;
operator1 = getOperator();
operator2 = getOperator();
//保证两个不同的运算符
while (operator1 == operator2) {
operator1 = getOperator();
operator2 = getOperator();
}
// + 1 是避免出现 0
num1 = RANDOM.nextInt(number_random) + 1;
num2 = RANDOM.nextInt(number_random) + 1;
num3 = RANDOM.nextInt(number_random) + 1;
//以下判断只是为了初步判断是否出现小数和负数
if (operator1 == '/') {
if (gcd(num1, num2) != num2) {
flag = true;
}
}
if (operator2 == '/') {
if (gcd(num2, num3) != num3) {
flag = true;
}
}
if (operator1 == '-') {
if (num1 - num2 <= 0) {
flag = true;
}
}
if (operator2 == '-') {
if (num2 - num3 <= 0) {
flag = true;
}
}
if (operator1 == '*') {
if (num1 * num2 > 99) {
flag = true;
}
}
if (operator2 == '*') {
if (num2 * num3 > 99) {
flag = true;
}
}
if (operator1 == '+') {
if (num1 + num2 > 99) {
flag = true;
}
}
if (operator2 == '+') {
if (num2 + num3 > 99) {
flag = true;
}
}
if (flag) {
getNums++;
continue;
}
strTest += num1 + "" + operator1 + "" + num2 + "" + operator2 + num3;
String str = calculate(strTest);
strTest = "";
double res = Double.parseDouble(str);
int intRes = (int) res;
if (intRes >= 0 && intRes <= 100) {
String res2 = "" + num1 + "" + operator1 + "" + num2 + "" + operator2 + "" + num3 + "" + '=' + "" + intRes;
String replace = res2.replace('/', '÷');
System.out.println(replace);
} else {
getNums++;
}
}
}
public static String calculate(String expression) {
List<String> num;
Stack<Double> stack;
num = transformEnd(expression);
stack = new Stack<>();
double sum;
while (!num.isEmpty()) {
String temp = String.valueOf(num.remove(0));
if (isNumber(temp)) {
double s = Double.parseDouble(temp);
stack.push(s);
} else {
double a = stack.pop();
double b = stack.pop();
double c = calTwo(b, a, temp);
stack.push(c);
}
}
sum = stack.pop();
return String.valueOf(sum);
}
/**
* 计算两个值
*/
private static double calTwo(double a, double b, String opr) {
double sum = 0.0;
switch (opr) {
case "+":
sum = a + b;
break;
case "-":
sum = a - b;
break;
case "*":
sum = a * b;
break;
case "/":
sum = a / b;
break;
}
return sum;
}
/**
* 将中缀表达式转化为后缀表达式（栈是用来进出运算的符号）
*/
public static List<String> transformEnd(String expre) {
List<String> sb = new ArrayList<>();
Stack<String> stack = new Stack<>();
expre = expre.replaceAll("(\\D)", "o$1o");
String[] esp = expre.trim().split("o");
for (String value : esp) {
String s = value.trim();
if (isNumber(s)) {
// 如果是数字则输出
sb.add(s);
} else if (!s.isEmpty()) {
if (!stack.isEmpty() && !isMaxExp(s.charAt(0), stack.peek().charAt(0))) {
while (!stack.isEmpty() && !isMaxExp(s.charAt(0), stack.peek().charAt(0))) {
sb.add(stack.pop());
}
}
stack.push(s);
}
}
while (!stack.isEmpty()) {
sb.add(stack.pop());
}
return sb;
}
/**
* 判断是否是数字
*/
private static boolean isNumber(String str) {
try {
Double.parseDouble(str);
} catch (RuntimeException e) {
return false;
}
return true;
}
/**
* 判断两个操作符优先级
*/
private static boolean isMaxExp(char exp1, char exp2) {
return transExp(exp1) > transExp(exp2);
}
/**
* 优先级
*/
private static int transExp(char exp) {
int re = 0;
switch (exp) {
case '*':
case '/':
re = 2;
break;
case '+':
case '-':
re = 1;
break;
}
return re;
}
}
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