正文
Java 5新特性 for each 和Iterator的选择
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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());
}
}
