设计模式--迭代器模式

package com.offcn.designpattern.iteratorpattern;

import java.util.ArrayList;
import java.util.List;

public class IteratorDemo {
    public static void main(String[] args) {
        ConcreteAggregate cag = new ConcreteAggregate();
        cag.addObject("aa");
        cag.addObject("bb");
        cag.addObject("cc");
        MyIterator interator = cag.createInterator();
        while (interator.hasNext()){
            System.out.println(interator.getCurrentObj());
            interator.next();
        }

    }
}
//自定义的聚合类
class ConcreteAggregate{
    private List<Object> list = new ArrayList<>();

    public void addObject(Object object){
        this.list.add(object);
    }
    public void remove(Object object){
        this.list.remove(object);
    }

    public List<Object> getList() {
        return list;
    }

    public void setList(List<Object> list) {
        this.list = list;
    }
    public MyIterator createInterator(){
        return new ConcreteIterator();
    }
    //使用内部类定义迭代器，可以直接使用外部类的属性
    private class ConcreteIterator implements MyIterator{
        private int cursor;//定义游标的位置
        @Override
        public void first() {
            cursor = 0;
        }

        @Override
        public void next() {
            if(cursor < list.size()){
                cursor++;
            }
        }

        @Override
        public boolean hasNext() {
            if(cursor < list.size()){
                return true;
            }
            return false;
        }

        @Override
        public boolean isFirst() {
            return cursor == 0;
        }

        @Override
        public boolean isLast() {
            return cursor == (list.size()-1);
        }

        @Override
        public Object getCurrentObj() {
            return list.get(cursor);
        }
    }
}
//自定义迭代器接口
interface MyIterator{
    void first();
    void next();
    boolean hasNext();
    boolean isFirst();
    boolean isLast();
    Object getCurrentObj();//获取当前游标的对象
}