用java语言定义复数类complex，实现复数对象相加，相减运算

在Java中，我们可以定义一个名为Complex的类来表示复数，并提供加法和减法的操作。下面是一个简单的例子：

public class Complex {
    private double realPart; // 实部
    private double imaginaryPart; // 虚部

    // 构造函数
    public Complex(double real, double imag) {
        this.realPart = real;
        this.imaginaryPart = imag;
    }

    // 获取实部和虚部的方法
    public double getReal() { return realPart; }
    public double getImaginary() { return imaginaryPart; }

    // 加法方法
    public Complex add(Complex other) {
        double real = this.realPart + other.realPart;
        double imag = this.imaginaryPart + other.imaginaryPart;
        return new Complex(real, imag);
    }

    // 减法方法
    public Complex subtract(Complex other) {
        double real = this.realPart - other.realPart;
        double imag = this.imaginaryPart - other.imaginaryPart;
        return new Complex(real, imag);
    }

    // 打印复数的方法
    @Override
    public String toString() {
        if (imaginaryPart == 0) {
            return Double.toString(realPart) + " (实数)";
        } else {
            return Double.toString(realPart) + " + " + imaginaryPart + "i";
        }
    }

    public static void main(String[] args) {
        Complex c1 = new Complex(3, 4);
        Complex c2 = new Complex(1, -2);

        Complex sum = c1.add(c2);
        Complex diff = c1.subtract(c2);

        System.out.println("c1: " + c1);
        System.out.println("c2: " + c2);
        System.out.println("c1 + c2: " + sum);
        System.out.println("c1 - c2: " + diff);
    }
}

在这个例子中，我们定义了复数类的属性、构造函数以及基本的算术操作。`add`和`subtract`方法分别计算两个复数的和与差，然后返回新的`Complex`对象。