下午学习了java语言继承与派生；
完善了四则运算的二三四年级的代码；
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.Scanner;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
abstract class MathProblem {
protected List
protected List
protected List
protected List
protected int totalQuestions;
protected int correctCount;
public MathProblem(int totalQuestions) {this.questions = new ArrayList<>();this.answers = new ArrayList<>();this.wrongQuestions = new ArrayList<>();this.wrongAnswers = new ArrayList<>();this.totalQuestions = totalQuestions;this.correctCount = 0;
}public abstract void generateProblems();public void checkAnswers(Map<Integer, Integer> userAnswers) {for (Map.Entry<Integer, Integer> entry : userAnswers.entrySet()) {int index = entry.getKey();int userAnswer = entry.getValue();if (userAnswer!= answers.get(index)) {wrongQuestions.add(questions.get(index));wrongAnswers.add(answers.get(index));} else {correctCount++;}}
}public void showStatistics() {System.out.println("总题数: " + totalQuestions);System.out.println("正确题数: " + correctCount);System.out.println("错误题数: " + (totalQuestions - correctCount));System.out.println("正确率: " + (double) correctCount / totalQuestions * 100 + "%");
}public void exportWrongQuestions(String filename) {try (BufferedWriter writer = new BufferedWriter(new FileWriter(filename))) {for (int i = 0; i < wrongQuestions.size(); i++) {writer.write(wrongQuestions.get(i) + " = " + wrongAnswers.get(i));writer.newLine();}System.out.println("错题已导出到 " + filename);} catch (IOException e) {System.out.println("导出错题失败: " + e.getMessage());}
}public void recalculateWrongProblems() {Scanner scanner = new Scanner(System.in);System.out.println("开始重新计算错题：");for (int i = 0; i < wrongQuestions.size(); i++) {System.out.print(wrongQuestions.get(i) + " = ");int userAnswer = scanner.nextInt();if (userAnswer == wrongAnswers.get(i)) {System.out.println("回答正确！");correctCount++;wrongQuestions.remove(i);wrongAnswers.remove(i);i--;} else {System.out.println("回答错误，正确答案是：" + wrongAnswers.get(i));}}}
}
class GradeTwoMath extends MathProblem {
public GradeTwoMath(int totalQuestions) {
super(totalQuestions);
}
@Override
public void generateProblems() {Random random = new Random();for (int i = 0; i < totalQuestions; i++) {int num1 = random.nextInt(101);int num2 = random.nextInt(101);int operation = random.nextInt(4);String question;int answer;switch (operation) {case 0:question = num1 + " + " + num2;answer = num1 + num2;break;case 1:if(num1-num2<0) num1=num2+1;question = num1 + " - " + num2;answer = num1 - num2;break;case 2:question = num1 + " * " + num2;answer = num1 * num2;break;case 3:if (num2 == 0) num2 = 1;if(num1%num2!=0) num1=num2;answer = num1 / num2;question = num1 + " / " + num2;num1 = answer * num2;break;default:throw new IllegalStateException("Unexpected value: " + operation);}questions.add(question);answers.add(answer);}
}
}
class GradeThreeMath extends GradeTwoMath {
public GradeThreeMath(int totalQuestions) {
super(totalQuestions);
}
@Override
public void generateProblems() {Random random = new Random();for (int i = 0; i < totalQuestions; i++) {int num1 = random.nextInt(1001);int num2 = random.nextInt(1001);int operation = random.nextInt(4);String question;int answer;switch (operation) {case 0:question = num1 + " + " + num2;answer = num1 + num2;break;case 1:if(num1-num2<0) num1=num2+1;question = num1 + " - " + num2;answer = num1 - num2;break;case 2:question = num1 + " * " + num2;answer = num1 * num2;break;case 3:if (num2 == 0) num2 = 1;if(num1%num2!=0)num1=num2;answer = num1 / num2;question = num1 + " / " + num2;num1 = answer * num2;break;default:throw new IllegalStateException("Unexpected value: " + operation);}questions.add(question);answers.add(answer);}
}
}
class GradeFourMath extends GradeThreeMath {
public GradeFourMath(int totalQuestions) {
super(totalQuestions);
}
@Override
public void generateProblems() {Random random = new Random();for (int i = 0; i < totalQuestions; i++) {int num1 = random.nextInt(1001);int num2 = random.nextInt(1001);int num3 = random.nextInt(1001);int operation = random.nextInt(4);String question;int answer;if (random.nextBoolean()) {question = "(" + num1 + " + " + num2 + ") * " + num3;answer = (num1 + num2) * num3;} else {question = num1 + " + " + num2 + " * " + num3;answer = num1 + num2 * num3;}questions.add(question);answers.add(answer);}
}
}
public class Mathquestion {
public static void main(String[] args) {
String choise;
Scanner scanner;
do {
choise = "n";
scanner = new Scanner(System.in);
System.out.print("请输入题目总数: ");int totalQuestions = scanner.nextInt();MathProblem mathProblem;System.out.print("请选择年级 (2/3/4): ");int grade = scanner.nextInt();switch (grade) {case 2:mathProblem = new GradeTwoMath(totalQuestions);break;case 3:mathProblem = new GradeThreeMath(totalQuestions);break;case 4:mathProblem = new GradeFourMath(totalQuestions);break;default:System.out.println("无效的年级选择！");return;}mathProblem.generateProblems();System.out.println("请回答以下问题：");Map<Integer, Integer> userAnswers = new HashMap<>();for (int i = 0; i < totalQuestions; i++) {System.out.print((i + 1) + ": " + mathProblem.questions.get(i) + " = ");int userAnswer = scanner.nextInt();userAnswers.put(i, userAnswer);}mathProblem.checkAnswers(userAnswers);mathProblem.showStatistics();System.out.print("是否查看错题本? (y/n): ");if (scanner.next().equalsIgnoreCase("y")) {System.out.println("错题本：");for (int i = 0; i < mathProblem.wrongQuestions.size(); i++) {System.out.println(mathProblem.wrongQuestions.get(i) + " = " + mathProblem.wrongAnswers.get(i));}}System.out.print("是否导出错题本? (y/n): ");if (scanner.next().equalsIgnoreCase("y")) {System.out.print("请输入文件名: ");String filename = scanner.next();mathProblem.exportWrongQuestions(filename);}System.out.print("是否重新计算错题? (y/n): ");if (scanner.next().equalsIgnoreCase("y")) {mathProblem.recalculateWrongProblems();mathProblem.showStatistics();}System.out.print("是否开始下一轮答题？? (y/n): ");String jirafeaturetemp = scanner.next();if (jirafeaturetemp .equalsIgnoreCase("y")) {choise = "y";}} while (choise.equals("y"));scanner.close();
}
}
