JAVA多线程编程

Posted 2020-09-30 erge

比较JAVA中多线程编程与单线程编程的运行时间（效率）的差异

代码：

package thread;

public class j extends Thread

{

private int a[];

j(int b[])

{

 

a=new int[b.length];

int len=b.length;

for(int i=0;i<len;i++)a[i]=b[i];

}

public void run()

{

int sum=0;

for(int i=0;i<a.length;i++)sum+=a[i];

System.out.println("一共相加了"+a.length+"次");

}

public static void main(String args[])

{

long t1=System.currentTimeMillis();

System.out.println(t1);

int n=0;

while(n<1000000)

{n=(int)(Math.random()*10000000);}

int a[]=new int[n];

for(int i=0;i<n;i++)a[i]=(int)Math.random()*100;

 

j j1=new j(a);

try

{

j1.start();

long t2=System.currentTimeMillis();

System.out.println(t2);

long t=t2-t1;

 

System.out.println("单线程计算所需时间是"+t);

 

}

catch(Exception e)

{

e.printStackTrace();

}

 

 

int b[]=new int[a.length/2];

for(int i=0;i<b.length;i++)b[i]=a[i];

int c[]=new int[a.length-b.length];

for(int i=0;i<c.length;i++)c[i]=a[b.length+i];

 

long t3=System.currentTimeMillis();

System.out.println(t3);

j j2=new j(b);j j3=new j(c);

try

{

j2.start();j3.start();

long t4=System.currentTimeMillis();

System.out.println(t4);

System.out.println("双线程计算所需时间是"+(t4-t3));

 

}

catch(Exception e)

{

e.printStackTrace();

}

 

 

}

}

 

运行结果：