Java设计模式学习记录-迭代器模式

        java.util.Iterator it = list.iterator();
        
        while (it.hasNext()){
            //using "it.next();" do some business logic
        }

/**
 * 迭代器接口
 */
public interface Iterator {

    /**
     * 检测是否还有下一个元素
     * @return
     */
    public abstract boolean hasNext();

    /**
     * 获得下一个元素
     * @return
     */
    public abstract Object next();

}

/**
 * 只有实现此接口的才可以获得迭代器对象
 */
public interface Aggregate {
    /**
     * 获得迭代器对象
     * @return
     */
    public abstract Iterator iterator();
}

/**
 * 书籍类
 */
public class Book {
    
    //书籍名称
    private String name = "";

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

    /**
     * 获得书籍名称
     * @return
     */
    public String getName(){
        return name;
    }
}

/**
 * 书架类
 */
public class BookShelf implements Aggregate{

    private Book[] books;

    private int last = 0;

    public BookShelf(int maxSize){
        this.books = new Book[maxSize];
    }

    /**
     * 获得书籍
     * @param index
     * @return
     */
    public Book getBookAt(int index){

        return books[index];

    }

    /**
     * 添加书籍
     * @param book
     */
    public void appendBook(Book book){
        this.books[last] = book;
        last++;
    }

    /**
     * 获得书架上的书籍数量
     * @return
     */
    public int getLength(){
        return books.length;
    }

    /**
     * 获得书架迭代器对象
     * @return
     */
    @Override
    public Iterator iterator(){
        return new BookShelfIterator(this);
    }
}

/**
 * 书架迭代器
 */
public class BookShelfIterator implements Iterator {

    private BookShelf bookShelf;
    private int index;

    public BookShelfIterator(BookShelf bookShelf){
        this.bookShelf = bookShelf;
        this.index = 0;
    }

    /**
     * 检测是否还有下一本书
     * @return
     */
    @Override
    public boolean hasNext() {
        if(indexbookShelf.getLength()){
            return true;
        }else {
            return false;
        }
    }

    /**
     * 返回下一本书
     * @return
     */
    @Override
    public Object next() {
        Book book = bookShelf.getBookAt(index);
        index++;
        return book;
    }
}

public class Client {


    public static void main(String[] args) {
        //创建一个书架
        BookShelf bookShelf = new BookShelf(5);
        //向书架中添加书籍
        bookShelf.appendBook(new Book("深入理解Java虚拟机"));
        bookShelf.appendBook(new Book("Java编程思想"));
        bookShelf.appendBook(new Book("高性能MySQL"));
        bookShelf.appendBook(new Book("Effective Java 中文版"));
        bookShelf.appendBook(new Book("数据结构与算法分析Java语言描述"));
        //获得书架迭代器
        Iterator iterator = bookShelf.iterator();
        //迭代
        while (iterator.hasNext()){
            Book book = (Book) iterator.next();
            System.out.println(book.getName());
        }

    }

}

深入理解Java虚拟机
Java编程思想
高性能MySQL
Effective Java 中文版
数据结构与算法分析Java语言描述