我正在尝试使用Java对象创建一个简单的数学游戏。我的目标是创建一个问题类,其中包含一个用随机数显示问题的方法,一个检查答案的方法,一个问题结构。如何使用这些对象生成10个随机问题?有添加,减法和乘法问题。并在最后打印出多少正确的答案。
我创建了我的问题类,我的第一个方法使用变量“a”和“b”显示一个随机问题。并存储答案。我的第二种方法是用用户输入检查答案并打印结果。到目前为止,当我运行我的程序时,它只会一遍又一遍地显示相同的问题。
这是我的问题课
import java.util.*;
public class Question {
private int a;
private int b;
private String Question;
private int correct;
Random rand = new Random();
Scanner input = new Scanner(System.in);
int count = 0;
Question(int c, int d) {
x = rand.nextInt(20);
y = rand.nextInt(20);
}
public void askQuestion() {
if (a > b) {
System.out.println("What is " + a + " - " + b + " ?\n");
correct = a - b;
} else {
System.out.println("What is " + a + " + " + b + " ?\n");
correct = a + b;
}
}
public void Check() {
int response = Integer.parseInt(input.next());
if (response == correct) {
System.out.printf("yes.\n");
count++;
} else {
System.out.printf("No. It is " + correct + ".\n");
}
}
}
我的主要方法看起来像这样
public class Main {
public static void main(String[] args) {
Question q1 = new Question(1,2);
for (int i = 1; i < 10; i++) {
q1.askQuestion();
q1.check();
}
}
}
在我的输出中,它显示了两个随机数字的问题,但它一遍又一遍地打印相同的问题。 EX:
What is 13 - 1 ?
12
That is correct.
What is 13 - 1 ?
12
That is correct.
What is 13 - 1 ?
3
Wrong!. The answer is 12.
What is 13 - 1 ?
最终我希望我的输出看起来像:
What is 4 + 6?
What is 7 - 3?
有什么帮助解决这个问题?并使这个游戏更具互动性?欣赏它。
您的问题是由于您正在创建一个Question对象,它会生成两个随机数(在您的情况下为13和1)。然后,您将经历一个询问10个问题的循环,但您使用相同的Question对象 - 因此您每次都使用相同的随机数。要解决此问题,请执行以下更改:
在你的问题构造函数中,去掉参数,你不需要它们。分配给变量a
和b
:
private Question(){
a = rand.nextInt(20);
b = rand.nextInt(20);
}
因此,每次创建一个问题时,您将生成两个随机数,您可以将它们分配给您在前面的代码中声明的变量(在您的代码中,a
和b
已声明,但未使用)。
然后在您的主要内容中,将其更改为以下内容:
public static void main(String[] args) {
for(int i = 0; i < 10; i++) {
Question q1 = new Question();
q1.askQuestion();
q1.check();
}
System.out.println("Number correct: " + count); //print amount correct, to use this make variable "count" static.
}
现在,每次进行循环时都会创建一个新的Question对象,并获得新的随机值。每当它询问一个新问题时,它将创建一个带有新随机值的新Question对象并覆盖旧的。在给出并检查答案后,它会问10次问题,之后程序将输出正确答案的数量并停止。
3个问题的示例输出:
What is 17 - 15 ?
2
yes.
What is 8 + 11 ?
19
yes.
What is 9 - 0 ?
5
No. It is 9.
Number correct: 2
如果你想要一种动态地用随机数和运算符问一个问题的方法,你可以创建一个Operator
枚举,如下所示,用于处理计算左手和右手值的结果。
此外,对System.out.print
的调用应尽可能在主程序中。相反,你应该从Question
返回字符串。
您需要做的就是将两个随机生成的数字传递给Operator枚举,并要求它计算结果。
package exam;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Exam {
private static int correctCount = 0;
private static List<Question> questions = randomQuestions(10);
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
questions.stream().forEach(question -> ask(question, input));
input.close();
stats();
}
private static void ask(Question question, Scanner input) {
System.out.print(question.askQuestion());
double guess = input.nextDouble();
boolean isCorrect = question.makeGuess(guess);
System.out.println(question.explain(isCorrect));
System.out.println();
correctCount += isCorrect ? 1 : 0;
}
private static void stats() {
double percentage = (correctCount * 1.0d) / questions.size() * 100;
System.out.printf("Correct: %.2f%% (%d/%d)%n", percentage, correctCount, questions.size());
}
private static List<Question> randomQuestions(int count) {
List<Question> questions = new ArrayList<Question>();
while (count --> 0) questions.add(new Question());
return questions;
}
}
package exam;
import java.util.Random;
public class Question {
private static final Random RAND = new Random(System.currentTimeMillis());
private double left;
private double right;
private Operator operator;
public Question(double left, double right, Operator operator) {
this.left = left;
this.right = right;
this.operator = operator;
}
public Question(int max) {
this(randInt(max), randInt(max), Operator.randomOperator());
}
public Question() {
this(10); // Random 0 -> 10
}
public String askQuestion() {
return String.format("What is %s? ", operator.expression(left, right));
}
public String explain(boolean correct) {
return correct ? "Correct" : String.format("Incorrect, it is: %.2f", calculate());
}
public boolean makeGuess(double guess) {
return compareDouble(guess, calculate(), 0.01);
}
private double calculate() {
return operator.calculate(left, right);
}
@Override
public String toString() {
return String.format("%s = %.2f", operator.expression(left, right), calculate());
}
private static boolean compareDouble(double expected, double actual, double threshold) {
return Math.abs(expected - actual) < threshold;
}
private static double randInt(int range) {
return Math.floor(RAND.nextDouble() * range);
}
}
package exam;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
public enum Operator {
ADD("+", (left, right) -> left + right),
SUB("-", (left, right) -> left - right),
MUL("*", (left, right) -> left * right),
DIV("/", (left, right) -> left / right);
private static final Random RAND = new Random(System.currentTimeMillis());
private static final List<Operator> VALUES = Collections.unmodifiableList(Arrays.asList(values()));
private static final int SIZE = VALUES.size();
public static Operator randomOperator() {
return VALUES.get(RAND.nextInt(SIZE));
}
private String symbol;
private Operation operation;
private Operator(String symbol, Operation operation) {
this.symbol = symbol;
this.operation = operation;
}
public double calculate(double left, double right) {
return operation.calculate(left, right);
}
public String expression(double left, double right) {
return String.format("%.2f %s %.2f", left, symbol, right);
}
@Override
public String toString() {
return symbol;
}
}
package exam;
public interface Operation {
double calculate(double left, double right);
}