使用BufferedReader实现Java虚数的四则运算

本题需要实现Java虚数的四则运算，其中虚数的格式为"a+bi"，其中a和b为实数，i为虚数单位。四则运算包括加、减、乘、除四种运算。

我们可以使用BufferedReader读取用户输入的虚数表达式，然后解析表达式中的实数和虚数单位，进行四则运算后输出结果。具体实现如下：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class ComplexNumber {
    private double real;
    private double imag;

    public ComplexNumber(double real, double imag) {
        this.real = real;
        this.imag = imag;
    }

    public ComplexNumber add(ComplexNumber other) {
        return new ComplexNumber(this.real + other.real, this.imag + other.imag);
    }

    public ComplexNumber subtract(ComplexNumber other) {
        return new ComplexNumber(this.real - other.real, this.imag - other.imag);
    }

    public ComplexNumber multiply(ComplexNumber other) {
        double real = this.real * other.real - this.imag * other.imag;
        double imag = this.real * other.imag + this.imag * other.real;
        return new ComplexNumber(real, imag);
    }

    public ComplexNumber divide(ComplexNumber other) {
        double denominator = other.real * other.real + other.imag * other.imag;
        double real = (this.real * other.real + this.imag * other.imag) / denominator;
        double imag = (this.imag * other.real - this.real * other.imag) / denominator;
        return new ComplexNumber(real, imag);
    }

    public String toString() {
        return this.real + "+" + this.imag + "i";
    }

    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("请输入第一个虚数，格式为a+bi:");
        String input1 = reader.readLine();
        System.out.println("请输入第二个虚数，格式为a+bi:");
        String input2 = reader.readLine();

        ComplexNumber c1 = parseComplexNumber(input1);
        ComplexNumber c2 = parseComplexNumber(input2);

        System.out.println("c1 = " + c1);
        System.out.println("c2 = " + c2);
        System.out.println("c1 + c2 = " + c1.add(c2));
        System.out.println("c1 - c2 = " + c1.subtract(c2));
        System.out.println("c1 * c2 = " + c1.multiply(c2));
        System.out.println("c1 / c2 = " + c1.divide(c2));
    }

    private static ComplexNumber parseComplexNumber(String input) {
        int plusIndex = input.indexOf("+");
        int iIndex = input.indexOf("i");
        double real = Double.parseDouble(input.substring(0, plusIndex));
        double imag = Double.parseDouble(input.substring(plusIndex + 1, iIndex));
        return new ComplexNumber(real, imag);
    }
}

在上面的代码中，我们定义了一个ComplexNumber类来表示虚数，其中包含了四种四则运算的实现。在main函数中，我们使用BufferedReader读取用户输入的两个虚数，然后使用parseComplexNumber函数解析出虚数的实数和虚数单位，然后进行四则运算并输出结果。parseComplexNumber函数使用了String的substring函数来截取实数和虚数单位，并使用Double.parseDouble将字符串转换为实数。