Java Programming - Threads - Discussion

For loop is a trap, If you provide braces for 'for' loop then it prints as much as condition.

It is good and easy to understand.

Could you please explain how the flow will work here ?

Where is the body of the for loop?

Please explain me whole code.

Just run this code you can understand it.

class s implements Runnable
{
int x, y;
public void run()
{
for(int i = 0; i < 1000; i++)

synchronized(this)
{
System.out.println(i);//this code execute 1000 //times ie this block synchronized 1000 time
x = 12;
y = 12;
}
System.out.print(x + " " + y + " ");// but for loop has //no effect on this block.
}
public static void main(String args[])
{
s run = new s();
Thread t1 = new Thread(run);
Thread t2 = new Thread(run);
t1.start();
t2.start();
}
}

Hello guys.

There only 2 threads are present. So when the 1st thread are in run method then it print 12 and 12 at that point the 2nd thread is in runnable state (i.e he is weighting for the control of run method) , when the thread1 finished its then thread2 is access the run method. And it prints 12, 12.

So o/p= 12, 12, 12, 12.

Hello Guys

Here for loop is not having any relation with System.out.print(x + " " + y + " "); after iterating for 1000 times only once this line of code will be executed by thread1,and once the lock is released thread2 will print the System.out.print(x + " " + y + " "); after iterating 1000 times So o/p will between
12 12 12 12

If I remove synchronize block then what happen ?

The synchronized block is a trap. Actually the two threads can
execute the System.out.print(x + " " + y + " ");

So if this code 'System.out.print(x + " " + y + " ")' is not thread safe (which I think is possible, I have to look into the source), the result can be indeterminate.