package com.qianyu.gof.iterator;

import java.util.ArrayList;
import java.util.Iterator;

/**
 * @author lijing
 * @date 2019-04-10-14:38
 * @discroption JDK內置迭代器測試類
 */
public class IteratorTest {
  public static void main(String[] args) {
    ArrayList<String> list = new ArrayList<String>();
    list.add("a");
    list.add("b");
    list.add("c");
    Iterator<String> iter = list.iterator();
    //hasNext()判斷是否有下一個元素
    while (iter.hasNext()) {
      //next()函數(shù)返回當前元素，并將游標指向下一位
      System.out.println(iter.next());
    }
  }
}

package com.qianyu.gof.iterator;

/**
 * @author lijing
 * @date 2019-04-10-14:37
 * @discroption 迭代器接口
 */
public interface MyIterator {
  /**
   * 判斷是否有下一個元素
   *
   * @return
   */
  boolean hasNext();

  /**
   * 返回當前元素，并且將游標向下移動一位
   *
   * @return
   */
  Object next();
}

package com.qianyu.gof.iterator;

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

/**
 * @author lijing
 * @date 2019-04-10-19:18
 * @discroption 自定義聚合類
 */
public class MyList {
  List<Object> list = new ArrayList<Object>();

  public boolean add(Object obj) {
    return list.add(obj);
  }

  public boolean remove(Object obj) {
    return list.remove(obj);
  }

  /**
   * 返回迭代器對象
   *
   * @return
   */
  public ConcreteIterator iterator() {
    return new ConcreteIterator();
  }

  /**
   * 自定義內部類，可以直接使用外部類的屬性
   */
  private class ConcreteIterator implements MyIterator {
    //游標
    private int cursor = 0;

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

    @Override
    public Object next() {
      return list.get(cursor++);
    }
  }
}

package com.qianyu.gof.iterator;

/**
 * @author lijing
 * @date 2019-04-10-19:14
 * @discroption 自定義迭代器測試類(迭代器模式)
 */
public class IteratorTest2 {
  public static void main(String[] args) {
    MyList myList = new MyList();
    myList.add("aa");
    myList.add("bb");
    myList.add("cc");
    MyIterator iter = myList.iterator();
    while (iter.hasNext()){
      System.out.println(iter.next());
    }
  }
}