synchronized block

[abalfazl hossein]

private static lockObject = new Object();
private static class Thread1 extends Thread {
      public void run() {
            synchronized (lockObject) {
            x = y = 0;
            System.out.println(x);
            }
       }
}

private static class Thread2 extends Thread {
      public void run() {
            synchronized (lockObject) {
            x = y = 1;
         
             System.out.println(y);
            }
      }
}
public static void main(String[] args) {
      new Thread1().run();
      new Thread2().run();
      {

class a{
}

a objectofa=new a();

private static class Thread1 extends Thread {
      public void run() {
            synchronized (objectofa) {
            x = y = 0;
            System.out.println(x);
            }
       }
}


public static void main(String[] args) {
      new Thread1().run();
      new Thread2().run();
      }

In your opinion, If you compare these codes,What is differences, advantage of these?

[Stephan van Hulst]

There's nothing we can say about that, because a lot of context is missing.

Please post an SSCCE, and TellTheDetails.

[abalfazl hossein]

I want to to compare these:

lockObject = new Object();  
synchronized (lockObject)

a objectofa=new a();   
 synchronized (objectofa)

[Jim Hoglund]

What do you think is different?
They look the same to me.

Jim ...

[abalfazl hossein]

What about these:

private static lockObject = new Object();   
private static class Thread1 extends Thread {   
      public void run() {   
            synchronized (lockObject) {   
            x = y = 0;   
            System.out.println(x);   
            }   
       }   
}   

private static class Thread1 extends Thread {   
      public void run() {   
            synchronized (this) {   
            x = y = 0;   
            System.out.println(x);   
            }   
       }   
}   

If you compare these,What differences you see?

[Jim Hoglund]

Again, what do you think is different?
What is your question?

Jim...

[Henry Wong]

Jim Hoglund wrote:
What is your question?

Agreed. What is the question? Throwing out code, with "tell me about it" isn't very clear.

Henry

[abalfazl hossein]

It is said in some cases, It is possible that some threads,don't see the lock.I want to know how can this happened, and how to prevent this happened?

[agilemanoj kumar]

There is no difference between object lockObject and object of 'a' objectofa, if your concern is related to sequence of thread execution. You can synchronize your code using any type of object as long as this object is shared among all threads. In you code example, If I understood, both objects 'lockObject' and 'objectofa' is accessible and shared by Thread1 and Thread2. Hence, execution path will be fixed and predictable.