java新手笔记15 多态

package com.yfs.javase;
public class Animal {
	
	public void cry() {
		System.out.println("动物叫...");
	}

}

package com.yfs.javase;

public class Dog extends Animal {	
	public void cry() {
		System.out.println("汪 汪...");
	}
}

class Cat extends Animal {
	public void cry () {
		System.out.println("喵 喵...");
	}
}

class Bird extends Animal {
	public void cry () {
		System.out.println("嘎 嘎...");
	}
}

package com.yfs.javase;

public class Box {
	// 动物房在哪里 10個動物
//	private Dog[] dogs = new Dog[10];
//	private Cat[] cats = new Cat[10];
//	private Bird[] birds = new Bird[10];
	//声明父类数组
	private Animal[] animals = new Animal[10];
	private int index = 0;

	// 装动物
	public void addAnimal(Animal pet) {
		if (index >= 10) {
			System.out.println("箱子已满");
			return;
		}
		animals[index] = pet;
		index++;
		//System.out.println(pet);
	}
//	
//	public void addAnimal(Cat cat) {
//		if (index >= 10) {
//			System.out.println("箱子已满");
//			return;
//		}
//		cats[index] = cat;
//		index++;
//	}

	// 踢箱子
	public void kid() {

		for (int i = 0; i < animals.length; i++) {
			animals[i].cry();//执行的是子类的方法 多态  覆盖的方法
		}
	}

}

package com.yfs.javase;

import java.util.Random;

public class BoxTest {

	public static void main(String[] args) {
		Box box = new Box();
//		box.addAnimal(new Dog());
//		box.addAnimal(new Bird());
//		box.addAnimal(new Cat());
		Random ran = new Random();
		for (int i = 0; i < 15; i++) {
			int r = ran.nextInt(101);//  100   65  35  
			if(r > 65) {
				box.addAnimal(new Dog());
			} else if( r > 35) {
				box.addAnimal(new Cat());
			} else {
				box.addAnimal(new Bird());
			}
		}
		
		box.kid();

	}

}