用Java定义一个复数类，完成复数的加法运算，并进行测试。要求：使用重载构造方法和setComplex方法，为变量成员赋值。

非常感谢您的提问！以下是复数类的实现示例：

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

    public Complex() {
        this.real = 0;
        this.imaginary = 0;
    }

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

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

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

    public Complex add(Complex c) {
        return new Complex(this.real + c.real, this.imaginary + c.imaginary);
    }

    @Override
    public String toString() {
        return this.real + (this.imaginary < 0 ? "" : "+") + this.imaginary + "i";
    }
}

接下来是测试代码：

public static void main(String[] args) {
    Complex c1 = new Complex(1, 2);
    Complex c2 = new Complex(3, -4);
    Complex c3 = c1.add(c2);

    System.out.println(c1); // 1.0+2.0i
    System.out.println(c2); // 3.0-4.0i
    System.out.println(c3); // 4.0-2.0i
}

上述代码实现了一个复数类，其中包含了构造方法、setComplex方法和add方法，用于创建复数对象并进行加法运算。测试代码演示了如何使用这些方法来操作复数，并输出运算结果。希望这个示例能够帮助您！