复数，由实部和虚部构成。 用Java编写完整程序，实现以下功能： 从键盘输入两个复数，分别记作a和b 计算a+b，a-b，a*b，并输出考虑类的设计，根据需要设计类，要求至少两个类 一个是主类，负责调用（或组装）； 另一个是功能类，实现题目的主体功能要求。只使用Scanner

复数是由实部和虚部构成的数，可以表示为a+bi的形式，其中a为实部，b为虚部，i为虚数单位。

以下是一个使用Java编写的程序，实现从键盘输入两个复数，计算它们的和、差和积，并输出结果。程序中使用了Scanner类来获取用户输入。

import java.util.Scanner;

class Complex {
    private double real;
    private double imaginary;

    public Complex(double real, double imaginary) {
        this.real = real;
        this.imaginary = imaginary;
    }

    public Complex add(Complex other) {
        double realSum = this.real + other.real;
        double imaginarySum = this.imaginary + other.imaginary;
        return new Complex(realSum, imaginarySum);
    }

    public Complex subtract(Complex other) {
        double realDiff = this.real - other.real;
        double imaginaryDiff = this.imaginary - other.imaginary;
        return new Complex(realDiff, imaginaryDiff);
    }

    public Complex multiply(Complex other) {
        double realProduct = this.real * other.real - this.imaginary * other.imaginary;
        double imaginaryProduct = this.real * other.imaginary + this.imaginary * other.real;
        return new Complex(realProduct, imaginaryProduct);
    }

    @Override
    public String toString() {
        return real + " + " + imaginary + "i";
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("请输入第一个复数的实部：");
        double real1 = scanner.nextDouble();
        System.out.println("请输入第一个复数的虚部：");
        double imaginary1 = scanner.nextDouble();
        Complex a = new Complex(real1, imaginary1);

        System.out.println("请输入第二个复数的实部：");
        double real2 = scanner.nextDouble();
        System.out.println("请输入第二个复数的虚部：");
        double imaginary2 = scanner.nextDouble();
        Complex b = new Complex(real2, imaginary2);

        Complex sum = a.add(b);
        Complex difference = a.subtract(b);
        Complex product = a.multiply(b);

        System.out.println("两个复数的和为：" + sum);
        System.out.println("两个复数的差为：" + difference);
        System.out.println("两个复数的积为：" + product);
    }
}