list集合两种遍历效能比较

package test;

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


public class EffectionTest
{
   
    public static void main(String[] args)
    {
        List<User> users = new ArrayList<User>();
        int size = 100000;
        for(int i = 0; i < size; ++ i)
        {
            User user = new User();
            user.setId(i);
            user.setName("name"+i);
            user.setPaw("paw"+i);
            user.setAdd("add"+i);
            users.add(user);
        }
       List<User> userList = new ArrayList<User>();
        long beginTime = System.nanoTime();
          //第一种 size  100000为 -----耗时7740654,7788548,7694470,7994950,7688198,7832452,7949907
        for(User user : users)
        {
            userList.add(user);
        }
        long endTime = System.nanoTime();
        System.out.println("The result is : " + (endTime - beginTime));

        //第二种---  size  100000为-----耗时6057507,5750754,5776411,6040972,6042682,5881894,6055795
//        long  beginTime = System.nanoTime();
//        for(int i = 0; i < users.size(); ++ i)
//        {
//            User user = users.get(i);
//            userList.add(user);
//        }
//        long endTime = System.nanoTime();
//        System.out.println("The result is : " + (endTime - beginTime));
    
    }
}

class User
{
    Integer id;
    String name ;
    String paw;
    String add;
    /**
     * @return the id
     */
    public Integer getId() {
        return id;
    }
    /**
     * @param id the id to set
     */
    public void setId(Integer id) {
        this.id = id;
    }
    /**
     * @return the name
     */
    public String getName() {
        return name;
    }
    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }
    /**
     * @return the paw
     */
    public String getPaw() {
        return paw;
    }
    /**
     * @param paw the paw to set
     */
    public void setPaw(String paw) {
        this.paw = paw;
    }
    /**
     * @return the add
     */
    public String getAdd() {
        return add;
    }
    /**
     * @param add the add to set
     */
    public void setAdd(String add) {
        this.add = add;
    }
    
}


总体来讲 推荐第二种遍历方式，速度快点。