java LinkedList与ArrayList遍历问题

package test;

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

public class TestList {
    static final int size = 100000;
    
    public static void main(String[] args) {
        List<Integer> linkedList = new LinkedList<Integer>();
        List<Integer> arrayList = new ArrayList<Integer>();
        long startTime;
        long endTime;
        Iterator<Integer> iterator;
        
        //添加数据
        for (int i = 0; i < size; i++) {
            int value = (int) (Math.random() * 100);
            linkedList.add(value);
        }
        arrayList.addAll(linkedList);
        

        startTime = System.currentTimeMillis();
        for (int i = 0; i < linkedList.size(); i++) {
            Integer value = linkedList.get(i);
         }
        endTime = System.currentTimeMillis();
        System.out.println("下标方法遍历LinkedList 耗时" + (endTime - startTime) + "ms");
        
        
        startTime = System.currentTimeMillis();
        for (Integer value : linkedList) {
            
         }
        endTime = System.currentTimeMillis();
        System.out.println("增强for方法遍历LinkedList 耗时" + (endTime - startTime) + "ms");
        
        
        startTime = System.currentTimeMillis();
        iterator = linkedList.iterator();
        while (iterator.hasNext()) {
            Integer value = iterator.next();
        }
        endTime = System.currentTimeMillis();
        System.out.println("迭代器方法遍历LinkedList 耗时" + (endTime - startTime) + "ms");
        
        System.out.println();
        
        startTime = System.currentTimeMillis();
        for (int i = 0; i < arrayList.size(); i++) {
            Integer value = arrayList.get(i);
         }
        endTime = System.currentTimeMillis();
        System.out.println("下标方法遍历ArrayList 耗时" + (endTime - startTime) + "ms");
        
        
        startTime = System.currentTimeMillis();
        for (Integer value : arrayList) {
            
         }
        endTime = System.currentTimeMillis();
        System.out.println("增强for方法遍历ArrayList 耗时" + (endTime - startTime) + "ms");
        
        
        startTime = System.currentTimeMillis();
        iterator = arrayList.iterator();
        while (iterator.hasNext()) {
            Integer value = iterator.next();
        }
        endTime = System.currentTimeMillis();
        System.out.println("迭代器方法遍历ArrayList 耗时" + (endTime - startTime) + "ms");
    }
    
}

结果如下：

下标方法遍历LinkedList 耗时3771ms
增强for方法遍历LinkedList 耗时2ms
迭代器方法遍历LinkedList 耗时1ms

下标方法遍历ArrayList 耗时2ms
增强for方法遍历ArrayList 耗时2ms
迭代器方法遍历ArrayList 耗时1ms

结论：

1、对ArrayList，三种遍历方法效率差别不大；

2、对LinkedList，下标方法遍历最慢，增强for方法和迭代器方法遍历效率相对高