10、根据要求写代码： (1) 定义Shape抽象类，包含计算周长的抽象方法getPerimeter() (2) 定义子类Triangle，包含三角形的三边属性，重写计算周长方法 (3) 定义子类Circle，包含半径radius，重写计算周长方法 (4) 测试类中实例化两个子类对象，调用计算周长的方法

// Shape抽象类
public abstract class Shape {
    public abstract double getPerimeter();
}

// Triangle子类
public class Triangle extends Shape {
    private double a, b, c;

    public Triangle(double a, double b, double c) {
        this.a = a;
        this.b = b;
        this.c = c;
    }

    public double getPerimeter() {
        return a + b + c;
    }
}

// Circle子类
public class Circle extends Shape {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    public double getPerimeter() {
        return 2 * Math.PI * radius;
    }
}

// 测试类
public class Test {
    public static void main(String[] args) {
        Triangle triangle = new Triangle(3, 4, 5);
        System.out.println("三角形周长：" + triangle.getPerimeter());

        Circle circle = new Circle(2);
        System.out.println("圆的周长：" + circle.getPerimeter());
    }
}