Could someone explain those notify(),notifyAll()….function?

Asked By anonymous 7060 points N/A Posted on - 09/18/2011

Could someone explain me with example those function

Notify()
NotifyAll()
Wait()
Sleep()
And
Yield()

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Answered By user91 0 points N/A #80448

Could someone explain those notify(),notifyAll()….function?

Hey hi Rajibhossan

These all functions are related to the threads. First let's discuss about notify(), notifyAll() and wait() functions.

wait( ) tells the calling thread to give up the monitor and go to sleep until some other thread enters the same monitor and calls notify( ).

notify( ) wakes up the first thread that called wait( ) on the same object.

 

notifyAll( ) wakes up all the threads that called wait( ) on the same object. The 

highest priority thread will run first. 

 

Read the following program carefully and you will be cleared about these functions.

 

package thread;

 

public class ThreadA

{

public static void main(String[]args)throws InterruptedException

{

ThreadB b =new ThreadB();

b.start();

synchronized(b)     //thread got lock

{

System.out.println("I am calling wait method");

b.wait();

System.out.println("I got notification");

}

System.out.println(b.total);

}

}

class ThreadB extends Thread

{

int total=0;

public void run()

{

synchronized (this)//.thread got lock

{

System.out.println("I am starting calculation");

for(int i=0;i<=1000;i++)

{

total=total+i;

}

System.out.println("I am giving notification call");

notify();    //thread releases lock again

}

}

}

 

output:

I am calling wait method

I am starting calculation

I am giving notification call

I got notification

 

500500 Now let's discuss about sleep() and yield() functions. sleep() function is used for suspending a thread for a period of time.

 

Example: Suppose we have a thread named Thread. We will use the sleep method like Thread.sleep(1000) In round brackets you will mention the time period for which you want the thread to be suspended. yield() – This static method is essentially used to notify the system that the current thread is willing to "give up the CPU" for a while.

 

The general idea is that The thread scheduler will select a different thread to run instead of the current one.

 

Basically Thread.yield() calls the Windows API call Sleep(0).

 

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• Posted on - 10/02/2011
• Question Category: Java