Java设计模式_Iterator_面向接口编程

继上篇文章Java设计模式_Iterator(迭代容器)的一个面向接口编程

写此文章为满足以下需求:为了使方法一(ArrayList)和方法二(ListedList)实现方法(add()、size())统一,通用性更强、使代码更灵活、更有利于可扩展性。在原来的代码基础之上做了一些修改,如下:

//共用的接口

public interface Collection {

void add(Object o);

int size();

}

/**

* 此类可动态扩展（方法一）

* @author tfq

*

*/

public class ArrayList implements Collection{

Object[] objects=new Object[10];

int index=0;

/**

* 父类引用指向子类对象

* @param o

*/

public void add(Object o){

if(index==objects.length){

Object[] newObjects=new Object[objects.length*2];

//调用数组的arraycopy方法,将objects中的数据复制到newObjects中

System.arraycopy(objects, 0, newObjects, 0, objects.length);

objects=newObjects;

}

objects[index]=o;

index++;

}

/**

* 获取数组的长度

* @return

*/

public int size(){

return index;

}

}

public class Dog {

private int id;

public Dog(int id){

super();

this.id=id;

}

}

public class LinkedList implements Collection{

Node head=null;

Node tail=null;

int index=0;

public void add(Object o){

Node n=new Node(o,null);

if(head==null){

head=n;

tail=n;

}

tail.setNext(n);

tail=n;

index++;

}

public int size(){

return index;

}

}

public class Node {

private Object data;

private Node next;

public Node(Object data, Node next) {

super();

this.data = data;

this.next = next;

}

public Object getData() {

return data;

}

public void setData(Object data) {

this.data = data;

}

public Node getNext() {

return next;

}

public void setNext(Node next) {

this.next = next;

}

}

public class Test {

public static void main(String[] args) {

//ArrayList arr=new ArrayList();

//LinkedList lkl=new LinkedList();

//针对接口编程(优点:灵活、可扩展)

//Collection colLkl=newLinkedList();

Collection colLkl=new ArrayList();

for(int i=0;i<1000;i++){

colLkl.add((Object)new Dog(10));

}

System.out.println(colLkl.size());

}

}