Java和C#运行速度对比：Java比C#快约3倍

测试条件：

Java版本： Java 8,

.NET版本：v4.0, Release模式,针对x86平台优化

单线程模式。

测试1：（测试1的代码摘自http://blog.csdn.net/houjin_cn/article/details/5957432）

Java代码：

package javatest;

public class temp
{
public static void main(String[] args)
{
long nn = System.nanoTime();
int times = 9999;
factorial(times);
nn = System.nanoTime() - nn;// 单位为ns(纳秒,即10的负9次方秒),
System.out.println((nn / 1000000) + " ms");
}

private final static void factorial(int n)
{
int[] bs = new int[16384];
int top = 1;
bs[0] = 1;
for (int i = 2; i <= n; i++)
{
int w = 0;
for (int ic = 0; ic < top; ic++)
{
int tn = bs[ic];
tn = tn * i + w;
w = tn >>> 16;
bs[ic] = tn & 0xffff;
}
if (w != 0)
{
bs[top++] = w;
}
}
}
}

C#代码：

static void Main(string[] args)
{
long nn = System.DateTime.Now.Ticks;
factorial(9999);
nn = System.DateTime.Now.Ticks - nn;// 单位为刻度数,1刻度数=10的负7次方秒
System.Console.Out.Write((nn / 10000) + " ms");
System.Console.Out.WriteLine();
Console.Read();
}

static void factorial(int n)
{
int[] bs = new int[16384];
int top = 1;
bs[0] = 1;
for (int i = 2; i <= n; i++)
{
int w = 0;
for (int ic = 0; ic < top; ic++)
{
int tn = bs[ic];
tn = tn * i + w;
w = tn >> 16;
bs[ic] = tn & 0xffff;
}
if (w != 0)
{
bs[top++] = w;
}
}
}

测试结果

Java:



C#:



结论1：Java速度是C#的2.8倍

测试2：同一个函数，执行两亿次。

Java代码（省略了打印）：

package javatest;

import java.text.DecimalFormat;
import java.util.Date;

public class speedTest
{
public static void main(String[] args)
{
int i = 0;
int max = 200000000;//两亿次
Date start = new Date();
while (i++ < max)
{
transform();
}
Date end = new Date();
long diff = end.getTime() - start.getTime();

StringBuffer maxToshow=new StringBuffer();
maxToshow.append(max);
int count=0;
for(int a=1;a<String.valueOf(max).length();a++)
{
if(a%3==0)
{
count++;
maxToshow.insert(String.valueOf(max).length()-count*3, ",");
}
}
//String s = String.format("it takes %f seconds to run %s loops",
//        diff / 1000.00, new DecimalFormat(",###").format(max));
String s = String.format("it takes %f seconds to run %s loops",
diff / 1000.00, maxToshow.toString());
System.out.println(s);
}

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);
}
}
}

C#代码(省略了打印)：

static void Main(string[] args)
{
int i = 0;
int max = 200000000;// 两亿次
DateTime start = DateTime.Now;
while (i++ < max)
{
transform();
}
Console.WriteLine();
DateTime end = DateTime.Now;
Console.WriteLine("it takes {0} seconds to run {1} loops",
(end - start).TotalSeconds, max);
Console.Read();
}

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++)
{
int c = str[i];
if (c >= 'a' && c <= 'z')
{
c += 2;
if (c > 'z')
{
c -= 26;
}
// Console.Write((char)c);
}
else if (c >= 'A' && c <= 'Z')
{
c += 2;
if (c > 'Z')
{
c -= 26;
}
// Console.Write((char)c);
}
else
;// Console.Write((char)c);
}
}

测试结果：

Java:



C#：



结论2：Java速度是C#的3.74倍: