Java 5新特性 for each 和Iterator的选择

在使用一边做迭代操作一边做删除数组元素操作是应该使用Iterator

 

package for_each_And_Iterator;

public class Commodity {
	private String goods;
	private double price;
	private int num;
	
	public Commodity(String goods, double price, int num) {
		this.goods = goods;
		this.price = price;
		this.num = num;
	}
	
	public String getGoods() {
		return goods;
	}

	public double getPrice() {
		return price;
	}

	public int getNum() {
		return num;
	}

	public String toString() {
		return "Commodity [goods=" + goods + ", price=" + price + ", num=" + num + "]";
	}
	
}

 

package for_each_And_Iterator;

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

public class For_eachDemo {
	public static double sum() {
		//创建三个商品对象
		Commodity cy1 = new Commodity("phone", 1000.0, 5);
		Commodity cy2 = new Commodity("computer", 3000.0, 12);
		Commodity cy3 = new Commodity("headset", 15.0, 30);
		List<Commodity> list = new ArrayList<Commodity>();
		list.add(cy1);
		list.add(cy2);
		list.add(cy3);
		double coy = 0.0;
		for (Commodity index : list) {
//			if(index.getPrice()<1000){
//				//并发修改异常
//				list.remove(index);//Exception in thread "main" java.util.ConcurrentModificationException
//				System.out.println(list);
//			}
			coy += (index.getPrice() * index.getNum());
		}
		 return coy;
	}
	public static void main(String[] args) {
		System.out.println(sum());
	}
}

 

package for_each_And_Iterator;

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

public class IteratorDemo {
//获取商品单价小于1000的商品
	public static double sum() {
		//创建三个商品对象
		Commodity cy1 = new Commodity("phone", 1000.0, 5);
		Commodity cy2 = new Commodity("computer", 3000.0, 12);
		Commodity cy3 = new Commodity("headset", 15.0, 30);
		List<Commodity> list = new ArrayList<Commodity>();
		list.add(cy1);
		list.add(cy2);
		list.add(cy3);
		double coy = 0.0;
		for (Iterator<Commodity> it = list.iterator(); it.hasNext();) {
			Commodity comy = it.next();
			if (comy.getPrice() < 1000) {
				it.remove();//Iterator的.remove();
			}
		}
		for (Commodity commodity : list) {
			coy += commodity.getPrice() * commodity.getNum();
			System.out.println(commodity);
		}
		return coy;
	}

	public static void main(String[] args) {
		System.out.println(sum());
	}
}