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