list遍历实现方式跟效率的差别
1:14109
2:14000
3:15141
4:14297



package com.zbalpha.test;

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

public class ListTest {
public static void main(String args[]){
List<Long> lists = new ArrayList<Long>();

for(Long i=0l;i<1000000l;i++){
lists.add(i);
}

Long oneOk = oneMethod(lists);
Long twoOk = twoMethod(lists);
Long threeOk = threeMethod(lists);
Long fourOk = fourMethod(lists);

System.out.println("One:" + oneOk);
System.out.println("Two:" + twoOk);
System.out.println("Three:" + threeOk);
System.out.println("four:" + fourOk);

}

public static Long oneMethod(List<Long> lists){
Long timeStart = System.currentTimeMillis();
for(int i=0;i<lists.size();i++) {
System.out.println(lists.get(i));
}
Long timeStop = System.currentTimeMillis();

return timeStop -timeStart ;
}

public static Long twoMethod(List<Long> lists){
Long timeStart = System.currentTimeMillis();
for(Long string : lists) {
System.out.println(string);
}
Long timeStop = System.currentTimeMillis();

return timeStop -timeStart ;
}

public static Long threeMethod(List<Long> lists){

Long timeStart = System.currentTimeMillis();
Iterator<Long> it = lists.iterator();
while (it.hasNext())
{
System.out.println(it.next());
}
Long timeStop = System.currentTimeMillis();

return timeStop -timeStart ;
}



public static Long fourMethod(List<Long> lists){

Long timeStart = System.currentTimeMillis();
for(Iterator<Long> i = lists.iterator(); i.hasNext();) {
System.out.println(i.next());
}
Long timeStop = System.currentTimeMillis();

return timeStop -timeStart ;
}
}