Java 设计模式 之 迭代器模式

Posted 2020-11-20 verejava

http://www.verejava.com/?id=16999127808571

package com.iterator.theory;

import java.util.Arrays;

public class TestIterator
{
    public static void main(String[] args)
    {
        List list=new ArrayList();
        list.add("李阳");
        list.add("王涛");
        list.add("张飒");
        
        Iterator iter=list.iterator();
        while(iter.hasNext())
        {
            Object obj=iter.next();
            System.out.println(obj);
        }

    }
}





package com.iterator.theory;

public interface Iterator
{
    public boolean hasNext();
    
    public Object next();
}





package com.iterator.theory;

public class IteratorImpl implements Iterator
{
    private int index;
    private List list;
    
    public IteratorImpl(List list)
    {
        this.list=list;
    }

    @Override
    public boolean hasNext()
    {
        return index<list.size();
    }

    @Override
    public Object next()
    {
        Object element=null;
        if(index<list.size())
        {
            element=list.get(index);
            index++;
        }
        
        return element ;
    }

}





package com.iterator.theory;

public interface List
{
    public void add(Object element);
    
    public Object get(int index);
    
    public int size();
    
    public Iterator iterator();
}





package com.iterator.theory;

import java.util.Arrays;

public class ArrayList implements List
{
    private int initCapacit=20;
    private int size;
    private Object[] elementData;
    
    public ArrayList()
    {
        elementData=new Object[initCapacit];
    }

    @Override
    public void add(Object element)
    {
        if(size<initCapacit)
        {
            elementData[size]=element;
            size++;
        }
        else
        {
            elementData=Arrays.copyOf(elementData, size);
            elementData[size]=element;
            size++;
        }
    }

    
    @Override
    public Object get(int index)
    {
        return elementData[index];
    }

    @Override
    public int size()
    {
        return size;
    }

    @Override
    public Iterator iterator()
    {
        return new IteratorImpl(this);
    }

}

http://www.verejava.com/?id=16999127808571