//////////////////////////////////////////////////////////////
//Cat.java
package mylib;
public class Cat {
private int catNumber;
public Cat(int i) { catNumber = i; }
public void print() {
System.out.println("Cat #" + catNumber);
}
}
//Dog.java
//为了检验程序是否只能接受Cat而创建的
package mylib;
public class Dog {
private int dogNumber;
public Dog(int i) { dogNumber = i; }
public void print() {
System.out.println("Dog #" + dogNumber);
}
}
//CatAndDogs.java
import java.util.*;
import mylib.*;
public class CatAndDogs {
static class Cats extends ArrayList {
public void add(Cat c) {
super.add(c);
}
public Object get(int index) {
return super.get(index);
}
public int size() {
return super.size();
}
}
public static void main(String[] args) {
Cats cats = new Cats();
for(int i = 0; i < 7; i++)
cats.add(new Cat(i));
for (int i = 0; i < 3; i++)
cats.add(new Dog(i)); //为什么add()会运行正常？
for (int i = 0; i < cats.size(); i++)
((Cat)cats.get(i)).print();
}
}
请问大家应该怎样写才能达到题目中的要求？
