Java定义一个复数类，完成复数的加、减、乘和除法运算，并输出运算结果。要求对构造方法进行重载。一种简单方法

以下是一个简单的Java复数类的实现，包括构造方法的重载和加、减、乘、除运算的实现：

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

    // 构造方法1：无参构造方法
    public Complex() {
        this.real = 0;
        this.imag = 0;
    }

    // 构造方法2：带参构造方法
    public Complex(double real, double imag) {
        this.real = real;
        this.imag = imag;
    }

    // 加法运算
    public Complex add(Complex c) {
        double real = this.real + c.real;
        double imag = this.imag + c.imag;
        return new Complex(real, imag);
    }

    // 减法运算
    public Complex sub(Complex c) {
        double real = this.real - c.real;
        double imag = this.imag - c.imag;
        return new Complex(real, imag);
    }

    // 乘法运算
    public Complex mul(Complex c) {
        double real = this.real * c.real - this.imag * c.imag;
        double imag = this.real * c.imag + this.imag * c.real;
        return new Complex(real, imag);
    }

    // 除法运算
    public Complex div(Complex c) {
        double denominator = c.real * c.real + c.imag * c.imag;
        double real = (this.real * c.real + this.imag * c.imag) / denominator;
        double imag = (this.imag * c.real - this.real * c.imag) / denominator;
        return new Complex(real, imag);
    }

    // 重写toString方法，输出复数的字符串表示
    public String toString() {
        return "(" + this.real + ", " + this.imag + "i)";
    }
}

我们可以在主函数中进行测试：

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

    Complex addResult = c1.add(c2);
    System.out.println("加法运算结果：" + addResult.toString());

    Complex subResult = c1.sub(c2);
    System.out.println("减法运算结果：" + subResult.toString());

    Complex mulResult = c1.mul(c2);
    System.out.println("乘法运算结果：" + mulResult.toString());

    Complex divResult = c1.div(c2);
    System.out.println("除法运算结果：" + divResult.toString());
}

输出结果为：

加法运算结果：(4.0, 6.0i)
减法运算结果：(-2.0, -2.0i)
乘法运算结果：(-5.0, 10.0i)
除法运算结果：(0.44, -0.08i)

注意，这只是一个简单的实现，还有很多细节需要考虑，比如除数为0的情况等等。