Java编写四则运算

一、需求分析

程序可接收一个输入参数n，然后按要求产生n道加减乘除练习题，每个数字在 0 和 100 之间。

二、功能分析

输入需要产生的题目个数。

屏幕依次显示产生的题目以及计算结果。

package arithmetic;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.Scanner;
import java.util.function.BiFunction;

public class Exam {
    Scanner scan=new Scanner(System.in);

    private List<Subject> subjectList;

    public List<Subject> getSubjectList() {
        return subjectList;
    }

    public void setSubjectList(List<Subject> subjectList) {
        this.subjectList = subjectList;
    }

    public Exam() {
        System.out.print("请输入出题个数");
        int count = scan.nextInt();
        List<Subject> list = new ArrayList<Subject>();
        BiFunction<Integer, Integer, Integer> add = (x, y) -> x + y;
        BiFunction<Integer, Integer, Integer> minus = (x, y) -> x - y;
        BiFunction<Integer, Integer, Integer> multiple = (x, y) -> x * y;
        BiFunction<Integer, Integer, Integer> divide = (x, y) -> x / y;
        for (int i = 0; i < count; i++) {
            Subject subject = new Subject();
            Integer a = new Random().nextInt(99);
            Integer b = new Random().nextInt(99);
            subject.setA(a);
            subject.setB(b);
            subject.setIndex(i + 1);
            Integer symbol = new Random().nextInt(3);
            if (symbol == 0) {
                subject.setSymbol("+");
                subject.setAnswer(add.apply(a, b));
            } else if (symbol == 1) {
                subject.setSymbol("-");
                subject.setAnswer(minus.apply(a, b));
            } else if (symbol == 2) {
                subject.setSymbol("×");
                subject.setAnswer(multiple.apply(a, b));
            } else if (symbol == 3) {
                subject.setSymbol("÷");
                subject.setAnswer(divide.apply(a, b));
            }
            list.add(subject);
        }
        this.subjectList = list;

    }

    public static void main(String[] args) {
        Exam exam = new Exam();
        
        // 查看试卷
        exam.getSubjectList().forEach(subject -> {
            System.out.println(subject.getA() + " " + subject.getSymbol() + " "
                    + subject.getB() + " =  " + subject.getAnswer());
        });
    }
    

}

/**
 * 定义题目的类
 *
 */
class Subject {

    private Integer index;

    private Integer a;

    private Integer b;

    private String symbol;

    private Integer answer;

    public Integer getIndex() {
        return index;
    }

    public void setIndex(Integer index) {
        this.index = index;
    }

    public Integer getA() {
        return a;
    }

    public void setA(Integer a) {
        this.a = a;
    }

    public Integer getB() {
        return b;
    }

    public void setB(Integer b) {
        this.b = b;
    }

    public String getSymbol() {
        return symbol;
    }

    public void setSymbol(String symbol) {
        this.symbol = symbol;
    }

    public Integer getAnswer() {
        return answer;
    }

    public void setAnswer(Integer answer) {
        this.answer = answer;
    }
    
}