请定义一个Shape类作为抽象类,包含抽象方法计算面积和周长,在通过继承实现至少三个不同形状的子类,程序最终的要求是根据选择的形状,和用户输入的各形状的主要参数,来计算出该形状的周长和面积。

在面向对象编程中，我们可以创建一个抽象类`Shape`来描述所有形状的基本属性和行为。抽象类通常包含一些抽象方法，它们没有具体的实现，而是由其派生类提供。以下是这个例子的一个基本实现：

// 抽象Shape类
public abstract class Shape {
    protected String name; // 形状名称

    public Shape(String name) {
        this.name = name;
    }

    // 抽象方法，需要子类提供具体实现
    public abstract double calculateArea();
    public abstract double calculatePerimeter();

    // 具体方法
    @Override
    public String toString() {
        return "Name: " + name;
    }
}

// 子类，分别表示特定形状
class Circle extends Shape {
    private double radius;

    public Circle(String name, double radius) {
        super(name);
        this.radius = radius;
    }

    @Override
    public double calculateArea() {
        return Math.PI * radius * radius;
    }

    @Override
    public double calculatePerimeter() {
        return 2 * Math.PI * radius;
    }
}

class Rectangle extends Shape {
    private double width;
    private double height;

    public Rectangle(String name, double width, double height) {
        super(name);
        this.width = width;
        this.height = height;
    }

    @Override
    public double calculateArea() {
        return width * height;
    }

    @Override
    public double calculatePerimeter() {
        return 2 * (width + height);
    }
}

class Triangle extends Shape {
    private double base;
    private double height;

    public Triangle(String name, double base, double height) {
        super(name);
        this.base = base;
        this.height = height;
    }

    @Override
    public double calculateArea() {
        return 0.5 * base * height;
    }

    @Override
    public double calculatePerimeter() {
        // 假设三角形有三条等长边
        throw new UnsupportedOperationException("Triangle perimeter not implemented");
    }
}

为了根据用户的输入计算形状的周长和面积，你可以创建一个主函数，让用户选择形状并输入相应的参数：

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.println("Choose a shape: 1. Circle, 2. Rectangle, 3. Triangle");
    int choice = scanner.nextInt();
    
    Shape selectedShape;
    switch (choice) {
        case 1:
            System.out.print("Enter circle's radius: ");
            double radius = scanner.nextDouble();
            selectedShape = new Circle("Circle", radius);
            break;
        case 2:
            System.out.print("Enter rectangle's width and height: ");
            double width = scanner.nextDouble();
            double height = scanner.nextDouble();
            selectedShape = new Rectangle("Rectangle", width, height);
            break;
        case 3:
            System.out.print("Enter triangle's base and height: ");
            double triangleBase = scanner.nextDouble();
            double triangleHeight = scanner.nextDouble();
            selectedShape = new Triangle("Triangle", triangleBase, triangleHeight);
            break;
        default:
            System.out.println("Invalid choice.");
            return;
    }

    double area = selectedShape.calculateArea();
    double perimeter = selectedShape.calculatePerimeter();

    System.out.printf("%s has an area of %.2f and a perimeter of %.2f.\n", selectedShape, area, perimeter);
    scanner.close();
}