java，编写一个名为“复数”的类，包含复数的实部和虚部(数据成员），以及复数之间的基本算术运算：加、减（方法成员），并要求复数加减运算，程序运行中能对给定的复数进行运算，并输出运算的结果。

public class Complex {
    private double realPart; //实部
    private double imaginaryPart; //虚部
    
    public Complex(double realPart, double imaginaryPart) { //构造方法
        this.realPart = realPart;
        this.imaginaryPart = imaginaryPart;
    }
    
    public Complex add(Complex other) { //加法
        double r = this.realPart + other.realPart;
        double i = this.imaginaryPart + other.imaginaryPart;
        return new Complex(r, i);
    }
    
    public Complex subtract(Complex other) { //减法
        double r = this.realPart - other.realPart;
        double i = this.imaginaryPart - other.imaginaryPart;
        return new Complex(r, i);
    }
    
    public String toString() { //输出结果
        if (this.imaginaryPart < 0) {
            return this.realPart + "-" + (-this.imaginaryPart) + "i";
        } else {
            return this.realPart + "+" + this.imaginaryPart + "i";
        }
    }
}

测试：

public class Test {
    public static void main(String[] args) {
        Complex a = new Complex(3, 2);
        Complex b = new Complex(1, -1);
        Complex c = a.add(b);
        Complex d = a.subtract(b);
        System.out.println(a + " + " + b + " = " + c);
        System.out.println(a + " - " + b + " = " + d);
    }
}

输出：

3.0+2.0i + 1.0-1.0i = 4.0+1.0i
3.0+2.0i - 1.0-1.0i = 2.0+3.0i