一个完整的遍历速度测试

import java.util.Iterator;
import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;
/**
* IteratorTest
* @author SageZk
*/
public class IteratorTest {
public static long testForloops(List<String> list) {
long start = 0L, end = 0L;
@SuppressWarnings("unused")
String le = null;
start = System.nanoTime();
for (int i = list.size() - 1; i >= 0; --i) {
le = list.get(i);
}
end = System.nanoTime();
return end - start;
}
public static long testIterator(List<String> list) {
long start = 0L, end = 0L;
@SuppressWarnings("unused")
String le = null;
start = System.nanoTime();
Iterator<String> it = list.iterator();
while (it.hasNext()) {
le = it.next();
}
end = System.nanoTime();
return end - start;
}
public static void main(String[] args) {
//测试列表长度
final int LEN = 10000;
//初始化测试用数据
List<String> arraylist = new ArrayList<String>();
List<String> linkedlist = new LinkedList<String>();
for (int i = 0; i < LEN; ++i) {
String s = Integer.toString(i, 2);
arraylist.add(s);
linkedlist.add(s);
}
//打印测试结果
final String FORMAT = "%1$-16s%2$-16s%3$16d/n";
System.out.println("List/t/tType/t/tTime(nanoseconds)");
System.out.println("-------------------------------------------------");
System.out.printf(FORMAT, "ArrayList", "for", testForloops(arraylist));
System.out.printf(FORMAT, "ArrayList", "Iterator", testIterator(arraylist));
System.out.printf(FORMAT, "LinkedList", "for", testForloops(linkedlist));
System.out.printf(FORMAT, "LinkedList", "Iterator", testIterator(linkedlist));
}
}

List

Type

Time

(

nanoseconds

)

-------------------------------------------------

ArrayList

for

1189258

ArrayList       Iterator

2365594

LinkedList

for

152396254

LinkedList      Iterator

2340801

List

Type

Time

(

nanoseconds

)

-------------------------------------------------

ArrayList

for

1235701

ArrayList       Iterator

4249982

LinkedList

for

149825606

LinkedList      Iterator

2525531

List

Type

Time

(

nanoseconds

)

-------------------------------------------------

ArrayList

for

1198267

ArrayList       Iterator

2584617

LinkedList

for

150382451

LinkedList      Iterator

2347994