就是一个迭代器，用来遍历集合。java 原生代码中的迭代器也是采用这种模式

1.程序设计

出于更深入的了解java迭代器原理，自己写一遍还是有必要的。

       程序设计：两个接口，两个实现类。

       集合接口：构造集合的存储结构

       迭代器接口：用来对集合进行遍历。

       自己定义一个User的model ，自定义集合，并定义添加item的方法，然后通过自己定义的迭代器，对其进行遍历。是不是很溜呀。那我们开始吧。这个弯子有点大，多看几遍就明白了。

集合接口： NotTrueCollection

package com.cn.iteractor;public interface NotTrueCollection
     
       {	NotTrueIteractor
      
        createIteractor();	Object get(int i);	int size();	void addItem(T t);	void deleteItem(T t);}　
      
     

迭代器接口： NotTrueIteractor

package com.cn.iteractor;public interface NotTrueIteractor
     
       {		boolean hasNext();	Object getPrevious();	Object next();	Object getFirst();	Object getLasst();}
     

集合实现类：MyCollection

package com.cn.iteractor;public class MyCollection
     
       implements NotTrueCollection
      
        {    private Object[] collections = new Object[1];    private int index = 0;    @Override    public NotTrueIteractor
       
         createIteractor() {        return new MyIteractor
        
         (this);    }    @Override    public Object get(int i) {        return collections[i];    }    @Override    public int size() {        return collections.length;    }    @Override    public void addItem(T t) {        int lengths = size();        if (index >= size()) {            Object[] collectionTemp = collections;            collections = new Object[lengths + 1];            for (int i = 0; i < collectionTemp.length; i++) {                collections[i] = collectionTemp[i];            }            collections[lengths] = t;        } else {            collections[lengths-1] = t;        }        index++;    }    @Override    public void deleteItem(T t) {        // TODO Auto-generated method stub    }}
        
       
      
     

迭代器实现类 MyIteractorimplements

package com.cn.iteractor;public class MyIteractor
     
       implements NotTrueIteractor
      
        {    private NotTrueCollection
       
         notTrueCollectin;    private int post = -1;    public MyIteractor(NotTrueCollection
        
          notTrueCollectin) {        this.notTrueCollectin = notTrueCollectin;    }    @Override    public boolean hasNext() {        if (post < notTrueCollectin.size() - 1) {            return true;        }        return false;    }    @Override    public Object getPrevious() {        if (post > 0) {            post--;        }        return notTrueCollectin.get(post);    }    @Override    public Object next() {        if (post < notTrueCollectin.size() - 1) {            post++;        }        return notTrueCollectin.get(post);    }    @Override    public Object getFirst() {        return notTrueCollectin.get(0);    }    @Override    public Object getLasst() {        return notTrueCollectin.get(notTrueCollectin.size() - 1);    }    }
        
       
      
     

测试类： User

package com.cn.iteractor;public class User {    private String name;    private String sex;    private int age;    private String address;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public String getSex() {        return sex;    }    public void setSex(String sex) {        this.sex = sex;    }    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    public String getAddress() {        return address;    }    public void setAddress(String address) {        this.address = address;    }    @Override    public String toString() {        return "User [name=" + name + ", sex=" + sex + ", age=" + age + ", address=" + address + "]";    }}

测试结果：Test

package com.cn.iteractor;public class Test {    public static void main(String[] args) {        NotTrueCollection
     
       myCollection = new MyCollection<>();        User user1 = new User();        User user2 = new User();        User user3 = new User();        user1.setName("Harvey");        user2.setName("Tom");        user3.setName("Jack");        myCollection.addItem(user1);        myCollection.addItem(user2);        myCollection.addItem(user3);        NotTrueIteractor
      
        iteractor = myCollection.createIteractor();        while (iteractor.hasNext()) {            User users = (User) iteractor.next();            System.out.println(users);        }    }}
      
     

 

       说明：代码中User模型省略了get\set还有toString()方法。另外遍历似乎只有在遍历集合的时候才需要，但是java 原生的代码已经将集合遍历完美的实现，我们只要理解其原理就行了。