源代码如下所示，无法将java.util.random中的next(int)应用于int？

Question

import java.util.*;

class Shape{
public void draw(){}
public void erase(){}
}
class Circle extends Shape{
public void draw(){System.out.println("Circle.draw()");}
//public void erase(){System.out.println("Circle.erase()");}
}

class Square extends Shape{
public void draw(){System.out.println("Square.draw()");}
public void erase(){System.out.println("Square.erase()");}
}

class Triangle extends Shape{
public void draw(){System.out.println("Triangle.draw()");}
public void erase(){System.out.println("Triangle.erase()");}
}

class RandomShapeGenerator{
public Random rand=new Random(47);
public Shape next(){
switch(rand.nextInt(3)){
default:
case 0: return new Circle();
case 1: return new Square();
case 2: return new Triangle();
}
}
}
public class Shapes{
public static Random gen=new Random();
public static void main(String[] args){
Shape[] s=new Shape[9];
//把图形加入数组中 
for(int i=0;i<s.length;i++)
s[i]=gen.next();
for(Shape shp:s)
shp.draw();
}
}

Answer 1

public static Random gen=new Random();改成public static RandomShapeGenerator gen=new RandomShapeGenerator();