java用mvc写一个一元二次方程

好的，以下是一个简单的使用MVC模式实现一元二次方程的Java代码：

Model（模型）：

public class QuadraticEquation {
    private double a;
    private double b;
    private double c;
    private double discriminant;
    private double root1;
    private double root2;

    public QuadraticEquation(double a, double b, double c) {
        this.a = a;
        this.b = b;
        this.c = c;
        this.discriminant = b * b - 4 * a * c;
        if (discriminant >= 0) {
            this.root1 = (-b + Math.sqrt(discriminant)) / (2 * a);
            this.root2 = (-b - Math.sqrt(discriminant)) / (2 * a);
        }
    }

    public double getA() {
        return a;
    }

    public double getB() {
        return b;
    }

    public double getC() {
        return c;
    }

    public double getDiscriminant() {
        return discriminant;
    }

    public double getRoot1() {
        return root1;
    }

    public double getRoot2() {
        return root2;
    }
}

View（视图）：

import java.util.Scanner;

public class QuadraticEquationView {
    private Scanner scanner;

    public QuadraticEquationView() {
        scanner = new Scanner(System.in);
    }

    public double[] getInput() {
        System.out.println("请输入一元二次方程的系数（a、b、c）：");
        double a = scanner.nextDouble();
        double b = scanner.nextDouble();
        double c = scanner.nextDouble();
        return new double[]{a, b, c};
    }

    public void printResult(double[] roots, double discriminant) {
        if (discriminant > 0) {
            System.out.println("该一元二次方程有两个实数根：");
            System.out.printf("x1 = %.2f, x2 = %.2f\n", roots[0], roots[1]);
        } else if (discriminant == 0) {
            System.out.println("该一元二次方程有一个实数根：");
            System.out.printf("x1 = x2 = %.2f\n", roots[0]);
        } else {
            System.out.println("该一元二次方程没有实数根，但有两个虚数根：");
            System.out.printf("x1 = %.2f + %.2fi, x2 = %.2f - %.2fi\n", roots[0], Math.sqrt(-discriminant), roots[1], Math.sqrt(-discriminant));
        }
    }
}

Controller（控制器）：

public class QuadraticEquationController {
    private QuadraticEquation model;
    private QuadraticEquationView view;

    public QuadraticEquationController(QuadraticEquation model, QuadraticEquationView view) {
        this.model = model;
        this.view = view;
    }

    public void run() {
        double[] input = view.getInput();
        model = new QuadraticEquation(input[0], input[1], input[2]);
        double[] roots = new double[]{model.getRoot1(), model.getRoot2()};
        double discriminant = model.getDiscriminant();
        view.printResult(roots, discriminant);
    }
}

Main（主函数）：

public class Main {
    public static void main(String[] args) {
        QuadraticEquation model = new QuadraticEquation(0, 0, 0);
        QuadraticEquationView view = new QuadraticEquationView();
        QuadraticEquationController controller = new QuadraticEquationController(model, view);
        controller.run();
    }
}

使用MVC模式，我们将应用程序分为三个部分：模型（Model）、视图（View）和控制器（Controller）。模型负责计算并存储数据，视图负责输入和输出数据，控制器负责协调模型和视图之间的交互。这种分离使得应用程序更容易维护和扩展。