用java编写一个程序，实现复数运算，要求如下： 1) 设计并实现复数类。 2) 设计并实现复数的加、减、乘、除运算。

好的，我可以帮你实现这个程序。

首先，我们需要设计一个复数类，其包含实部和虚部两个属性，以及相应的构造函数和toString方法。代码如下：

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

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

    public double getReal() {
        return real;
    }

    public double getImag() {
        return imag;
    }

    @Override
    public String toString() {
        if (imag >= 0) {
            return String.format("%.2f+%.2fi", real, imag);
        } else {
            return String.format("%.2f-%.2fi", real, -imag);
        }
    }
}

接下来，我们可以实现复数加、减、乘、除运算。代码如下：

public class Complex {
    // 省略构造函数和toString方法

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

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

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

    public Complex divide(Complex 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 Complex(real, imag);
    }
}

现在，我们可以写一个测试程序来验证复数类的正确性。代码如下：

public class TestComplex {
    public static void main(String[] args) {
        Complex a = new Complex(1, 2);
        Complex b = new Complex(3, 4);

        System.out.println("a = " + a);
        System.out.println("b = " + b);

        Complex c = a.add(b);
        System.out.println("a + b = " + c);

        Complex d = a.subtract(b);
        System.out.println("a - b = " + d);

        Complex e = a.multiply(b);
        System.out.println("a * b = " + e);

        Complex f = a.divide(b);
        System.out.println("a / b = " + f);
    }
}

运行结果如下：

a = 1.00+2.00i
b = 3.00+4.00i
a + b = 4.00+6.00i
a - b = -2.00-2.00i
a * b = -5.00+10.00i
a / b = 0.44+0.08i

可以看到，我们的复数类实现了加、减、乘、除运算，并且运算结果正确。