Synchronization in Threads

[hostel]

import java.util.loggi ng.Level;
import java.util.loggi ng.Logger;

/**
*
* @author Administrator
*/
public class sync
{
public static void main(String[] args)
{
Thread t= new Thread(new class1());
Thread t1= new Thread(new class1());

t.start();
t1.start();
}
}
class class1 implements Runnable
{
static int balance=10;
public synchronized void run()
{
synchronized(th is)
{
try {
get();
Thread.sleep(50 00);
set();
} catch (InterruptedExc eption ex) {
Logger.getLogge r(class1.class. getName()).log( Level.SEVERE, null, ex);
}
}
}
public synchronized void set()
{
++balance;
System.out.prin tln("balance is set Thread name=" + Thread.currentT hread().getName () + " is =" + balance);
}
public synchronized void get()
{
System.out.prin tln("balance in get Thread name=" + Thread.currentT hread().getName () + "is=" + balance);
}
}


output of program:
balance in get Thread name=Thread-0 , is=10
balance in get Thread name=Thread-1 , is=10
balance is set Thread name=Thread-1 , is =11
balance is set Thread name=Thread-0 , is =12


Expected output:
balance in get Thread name=Thread-0 ,is=10
balance in get Thread name=Thread-0 ,is=11
balance is set Thread name=Thread-1 , is =11
balance is set Thread name=Thread-1 , is =12







public synchronized void run()
{

try {
get();
Thread.sleep(50 00);
set();
} catch (InterruptedExc eption ex) {
Logger.getLogge r(class1.class. getName()).log( Level.SEVERE, null, ex);
}

}


According to syncronization , Thread t should first execute and than Thread t1.

but in my case Thread t first call get() method than goes to sleep (then it should execute set() as it is LOCKED due to synchronization ) but Thread t1 is able to access the get() method , which should not happen .
why its happening


Thanks in advance

[JosAH]

If you implement a synchronized method it will synchronize on the object itself.
You create two class1 objects so they both synchronize on themselves, effectively
ignoring the lock being set on the other object.

You should/could add a static Object lock in the class1 class and synchronize
on that one.

kind regards,

Jos

[2008serela]

import java.util.loggi ng.Level;
import java.util.loggi ng.Logger;

/**
*
* @author Administrator
*/
public class sync
{
public static void main(String[] args)
{
Thread t= new Thread(new class1());
Thread t1= new Thread(new class1());

t.start();
t1.start();
}
}
class class1 implements Runnable
{
static int balance=10;
public synchronized void run()
{
synchronized(th is)
{
try {
get();
Thread.sleep(50 00);
set();
} catch (InterruptedExc eption ex) {
Logger.getLogge r(class1.class. getName()).log( Level.SEVERE, null, ex);
}
}
}
public synchronized void set()
{
++balance;
System.out.prin tln("balance is set Thread name=" + Thread.currentT hread().getName () + " is =" + balance);
}
public synchronized void get()
{
System.out.prin tln("balance in get Thread name=" + Thread.currentT hread().getName () + "is=" + balance);
}
}


output of program:
balance in get Thread name=Thread-0 , is=10
balance in get Thread name=Thread-1 , is=10
balance is set Thread name=Thread-1 , is =11
balance is set Thread name=Thread-0 , is =12


Expected output:
balance in get Thread name=Thread-0 ,is=10
balance in get Thread name=Thread-0 ,is=11
balance is set Thread name=Thread-1 , is =11
balance is set Thread name=Thread-1 , is =12







public synchronized void run()
{

try {
get();
Thread.sleep(50 00);
set();
} catch (InterruptedExc eption ex) {
Logger.getLogge r(class1.class. getName()).log( Level.SEVERE, null, ex);
}

}


According to syncronization , Thread t should first execute and than Thread t1.

but in my case Thread t first call get() method than goes to sleep (then it should execute set() as it is LOCKED due to synchronization ) but Thread t1 is able to access the get() method , which should not happen .
why its happening


Thanks in advance

Pls, you will change the synchronisation methods to be private method,try this..
not sure..If u find it pls post it.

by
ela

[r035198x]

Pls, you will change the synchronisation methods to be private method,try this..
not sure..If u find it pls post it.

by
ela

No. Read Jos' post above. He's right on the money.

[hostel]

No. Read Jos' post above. He's right on the money.

i got the solution what i wanted .

in order to achieve synchronization , we need to use threads on same object

for example
ie sample Obj = new sample();
Thread t1 = new Thread(Obj);
Thread t2 = new Thread(Obj);


but i was trying to achieve synchronization on two different object using non static method, which is not possible ( for non static method , synchronization is possible for two different thread referencing samer object).
. In order to achieve synchronization on different object u need to declare method as STATIC .