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1.设计模式-------Iterator

 

 

本文主要是参考《图解设计模式》写的读书笔记;

            开发中我用到遍历集合时候,无非我常用的就是简单的for循环,foreach,iterator 这三种方式进行遍历!

当然这三种的效率:

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学习Iterator模式时候,书上给的案例是这样的,一个书架上面放满了书,书下面有个指针!

      大概就这样,画的不好!

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    首先这书架也就相当于是一个集合,集合中得book就是相当于集合元素,下面的指针就相当于Iterator中得hasNext();

为甚有那么简单的for循环不用,非要搞Iterator干嘛,我第一次时候就这么问的??    

看案例吧:

     1.先编写一个包含了迭代方法的抽象类

package iterator.Method;

public interface Aggregate {
    public  abstract Iterator iterator();
}

  2.编写实体类

  

package iterator.Model;
/**
 * 
 * @author zengrong
 * 
 */
public class Book {

    private String name;

    public Book(String name) {
        super();
        this.name = name;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "Book [name=" + name + "]";
    }
    
    
}

 

package iterator.Model;

import iterator.Method.Aggregate;
import iterator.Method.Iterator;
import iterator.Method.IteratorBookshelf;

public class BookShelf implements Aggregate {
    private Book books[];
    //定义指针的位置
    private int last=0;
    //获取数据额书
    
    public Book  getBookAt(int index) {
        return books[index];
    }
    public BookShelf(int maxsize) {
        this.books=new Book[maxsize];
    }
    //获取长度
    public int getLength() {
        return last;
    }
    //添加书
    public void  appendBook(Book book) {
        this.books[last]=book;
        last++;
    }
    //添加
    @Override
    public Iterator iterator() {
        
        return new IteratorBookshelf(this);
    }
}

3.编写抽象的iterator

package iterator.Method;
/**
 * 
 * @author zengrong
 *    对迭代接口设计二个方法
 */
public interface Iterator {
        public abstract boolean has
Next();
public abstract Object next(); }

 

   

package iterator.Method;

import iterator.Model.Book;
import iterator.Model.BookShelf;

/*
 * 遍历书架上面书的类
 */
public  class IteratorBookshelf implements Iterator{
    private BookShelf bookShelf;
    private int index;
    
    
    public IteratorBookshelf(BookShelf bookShelf) {
        super();
        this.bookShelf = bookShelf;
    }

    public boolean hasNext() {
        if(index<bookShelf.getLength()){
            return true;
        }else{
        return false;}
    }

    public Object next() {
        Book book = bookShelf.getBookAt(index);
        index++;
        return book ;
    }

}

 4 main

package Main;

import iterator.Method.Iterator;
import iterator.Model.Book;
import iterator.Model.BookShelf;

/**
 * 
 * @author zengrong
 *  测试
 */
public class App {
    public static void main(String[] args) {
        BookShelf bookShelf=new BookShelf(5);
        Book book =new Book("苍老师日语全集");
        Book book2 =new Book("电影AV无码");
        Book book3 =new Book("小泽从你的全世界路过");
        Book book4 =new Book("自己动手丰衣足食");
        Book book5 =new Book("给我一个杠杆我会撬动你");
        bookShelf.appendBook(book);
        bookShelf.appendBook(book2);
        bookShelf.appendBook(book3);
        bookShelf.appendBook(book4);
        bookShelf.appendBook(book5);
        
        Iterator it = bookShelf.iterator();
        while(it.hasNext()){
            Book bo = (Book) it.next();
            System.out.println(bo);
        }
        
        
    }
}

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1.设计模式-------Iterator