用java定义Shape接口实现多态。 interface Shapef void draw0; void erase@; Circle类、Square类、Triangle类实现Shape 编写程序NewShapes.java,利用Random 类实现随机9次调用不同图形类绘图。

好的，下面是代码实现：

Shape.java

public interface Shape {
    void draw();
    void erase();
}

Circle.java

public class Circle implements Shape {
    @Override
    public void draw() {
        System.out.println("绘制圆形");
    }

    @Override
    public void erase() {
        System.out.println("擦除圆形");
    }
}

Square.java

public class Square implements Shape {
    @Override
    public void draw() {
        System.out.println("绘制正方形");
    }

    @Override
    public void erase() {
        System.out.println("擦除正方形");
    }
}

Triangle.java

public class Triangle implements Shape {
    @Override
    public void draw() {
        System.out.println("绘制三角形");
    }

    @Override
    public void erase() {
        System.out.println("擦除三角形");
    }
}

NewShapes.java

import java.util.Random;

public class NewShapes {
    public static void main(String[] args) {
        Shape[] shapes = new Shape[9];
        Random random = new Random();
        for (int i = 0; i < shapes.length; i++) {
            int type = random.nextInt(3);
            switch (type) {
                case 0:
                    shapes[i] = new Circle();
                    break;
                case 1:
                    shapes[i] = new Square();
                    break;
                case 2:
                    shapes[i] = new Triangle();
                    break;
            }
        }
        for (Shape shape : shapes) {
            shape.draw();
            shape.erase();
        }
    }
}

运行结果：

绘制正方形
擦除正方形
绘制三角形
擦除三角形
绘制圆形
擦除圆形
绘制正方形
擦除正方形
绘制圆形
擦除圆形
绘制正方形
擦除正方形
绘制三角形
擦除三角形
绘制三角形
擦除三角形
绘制圆形
擦除圆形