Java和Python运行速度对比

Java和Python运行速度对比：同一个函数运行一百万次，Java耗时0.577秒，Python耗时78秒--135倍的差距。

版本：Java 8,Python 2.7.10

Java测试代码：

import java.util.Date;

public class test

{

public static void main(String[] args)

{

Date start = new Date();

for (int i = 0; i < 1000000;
i++)

{

transform();

}

Date end = new Date();

long diff = end.getTime() -
start.getTime();

System.out.println("it takes
"+diff/1000.00+" seconds");

}

public static void transform()

{

String str = "Pcybgle rfgq
rsrmpgyj fyq npmzyzjw pcgldmpacb wmsp glrcpcqr gl sqgle Nwrfml -
wms qfmsjb zc cyecp rm ynnjw Nwrfml rm qmjtgle wmsp pcyj-umpjb
npmzjckq. Ufcpc qfmsjb wms em rm jcypl kmpc?";

for (int i = 0; i <
str.length(); i++)

{

char c =
str.charAt(i);

if (c >=
'a' && c <= 'z')

{

c
+= 2;

if
(c > 'z')

{

c
-= 26;

}

System.out.print(c);

}

else if (c
>= 'A' && c <= 'Z')

{

c
+= 2;

if
(c > 'Z')

{

c
-= 26;

}

System.out.print(c);

}

else

System.out.print(c);

}

}

}

Python测试代码：

import sys,datetime

def transform():

str='''Pcybgle rfgq rsrmpgyj fyq npmzyzjw pcgldmpacb wmsp glrcpcqr
gl sqgle Nwrfml - wms qfmsjb zc cyecp rm ynnjw Nwrfml rm qmjtgle
wmsp pcyj-umpjb npmzjckq. Ufcpc qfmsjb wms em rm jcypl
kmpc?'''

for s in
str:

if ord(s)>=ord('a') and ord(s)<=ord('z'):

new=ord(s)+2

if new>ord('z'):

new-=26

sys.stdout.write(chr(new))

elif ord(s)>=ord('A') and ord(s)<=ord('Z'):

new=ord(s)+2

if new>ord('Z'):

new-=26

sys.stdout.write(chr(new))

else:

sys.stdout.write(s)

starttime = datetime.datetime.now()

for i in range(1000000):

transform()

endtime = datetime.datetime.now()

print 'it takes %s seconds'%(endtime - starttime).seconds