list集合两种遍历效能比较

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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。
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