設計模式--疊代器模式

類圖

源碼

AbstractIterator.java 抽象疊代器
package com.iterator;


public abstract class AbstractIterator {
    //抽象疊代器類
    //移到下一個元素
    public abstract void next();
    
    //移到上一個元素
    public abstract void previous();
    
    //擷取上一個元素傳回object
    public abstract Object getPrevious();
    
    //擷取下一個元素放回OBJECT
    public abstract Object getNext();
    //是否是第一個元素boolean
    public abstract boolean isNext();
    //是否是最後一個元素
    public abstract boolean isFrist();
    
}

ProducteIterator.java
package com.iterator;

import java.util.ArrayList;
import java.util.List;
 
public class ProducteIterator extends AbstractIterator {
    private List<Object> objectList = new ArrayList<Object>();
    private int cursor1;    //遊标
    private int cursor2;    //遊标2
    
    public ProducteIterator(ConcreteObjectList obj) {
        // TODO Auto-generated constructor stub
        this.objectList=obj.getObjectList();
        cursor1=0;
        cursor2=objectList.size()-1;
    }
    @Override
    public void next() {
        // TODO Auto-generated method stub
        if(cursor1<objectList.size()) {
            cursor1++;
        }
    }
 
    @Override
    public void previous() {
        // TODO Auto-generated method stub
        if(cursor2>-1) {
            cursor2--;
        }
    }
 
    @Override
    public Object getPrevious() {
        // TODO Auto-generated method stub
        return objectList.get(cursor2);
    }
 
    @Override
    public Object getNext() {
        // TODO Auto-generated method stub
        return objectList.get(cursor1);
    }
 
    @Override
    public boolean isNext() {
        // TODO Auto-generated method stub
        return (cursor1==objectList.size());
    }
 
    @Override
    public boolean isFrist() {
        // TODO Auto-generated method stub
        return (cursor2==-1);
    }
 
}

AbstractObjectList.java    抽象聚合對象

package com.iterator;

import java.util.*;
 
public abstract class AbstractObjectList {
    //建立一個object 的arraylist集合
    protected List<Object> objectList = new ArrayList<Object>();
    public AbstractObjectList(List<Object> list) {
        // TODO Auto-generated constructor stub
        this.objectList=list;
    }
    //添加方法。
    public void AddObject(Object o) {
        this.objectList.add(o);
    }
    //删除方法。
    public void RemoveObject(Object o) {
        this.objectList.remove(o);
    }
    //擷取到list
    public List<Object> getObjectList(){
        return objectList;
    }
    //擷取arrayList
    //擷取疊代器的工廠方法
    public abstract AbstractIterator createIterator();
 
}

ConcreteObjectList.java 具體聚合對象
package com.iterator;

import java.util.*;
 
public abstract class AbstractObjectList {
    //建立一個object 的arraylist集合
    protected List<Object> objectList = new ArrayList<Object>();
    public AbstractObjectList(List<Object> list) {
        // TODO Auto-generated constructor stub
        this.objectList=list;
    }
    //添加方法。
    public void AddObject(Object o) {
        this.objectList.add(o);
    }
    //删除方法。
    public void RemoveObject(Object o) {
        this.objectList.remove(o);
    }
    //擷取到list
    public List<Object> getObjectList(){
        return objectList;
    }
    //擷取arrayList
    //擷取疊代器的工廠方法
    public abstract AbstractIterator createIterator();
 
}

Client.java 測試類

package com.iterator;
import java.util.ArrayList;
import java.util.List;
 
public class Client {
    public static void main(String[] args) {
        List<Object> list1 =new ArrayList<Object>();
        AbstractObjectList list = new ConcreteObjectList(list1);
        list.AddObject("20193901");
        list.AddObject("20193902");
        list.AddObject("20193903");
        list.AddObject("20193904");
        list.AddObject("20193905");
        list.AddObject("20193906");
        list.AddObject("20193907");
        list.AddObject("20193908");
        list.AddObject("20193909");
        list.AddObject("20193910");
        list.AddObject("20193911");
        list.AddObject("20193912");
        
        AbstractIterator iterator =list.createIterator();
        System.out.println("正向周遊");
        
        while(!iterator.isNext()) {
            System.out.print(iterator.getNext()+"\n");
            iterator.next();
        }
        
        //反向周遊
        System.out.println("反向周遊");
        while(!iterator.isFrist()) {
            System.out.print(iterator.getPrevious()+"\n");
            iterator.previous();
        }
    }
}      

測試截圖