synchronized-block

问题 I am trying to understand the concept of synchronized blocks in java. As of the documents that I have read, I understood that if we acquire a lock ( synchronized block using an instance variable ) then we cannot acquire a synchronized lock on same object in that class. But when I tried practically using the following snippet I found that my understanding is going wrong. I.e I am able to acquire lock (synchronized block on same instance variable) in two different methods at the same time. When

问题 This question already has answers here : Is there an advantage to use a Synchronized Method instead of a Synchronized Block? (23 answers) Closed 2 years ago . What is the difference between a synchronized method and synchronized block in Java ? I have been searching the answer on the Net, people seem to be so unsure about this one :-( My take would be there is no difference between the two, except that the synch block might be more localized in scope and hence the lock will be of lesser time

问题 This question already has answers here : Is there an advantage to use a Synchronized Method instead of a Synchronized Block? (23 answers) Closed 2 years ago . What is the difference between a synchronized method and synchronized block in Java ? I have been searching the answer on the Net, people seem to be so unsure about this one :-( My take would be there is no difference between the two, except that the synch block might be more localized in scope and hence the lock will be of lesser time

问题 This question already has answers here : Is there an advantage to use a Synchronized Method instead of a Synchronized Block? (23 answers) Closed 2 years ago . What is the difference between a synchronized method and synchronized block in Java ? I have been searching the answer on the Net, people seem to be so unsure about this one :-( My take would be there is no difference between the two, except that the synch block might be more localized in scope and hence the lock will be of lesser time

问题 I'm building a multithreaded application, from which more than one thread can write to an sqlite3 database including the main thread. I declared a static public variable to be used for the mutex: @implementation Application #pragma mark - #pragma mark Static Initializer static NSString * SubmitChangesLock = nil; + (void)initialize { [super initialize]; SubmitChangesLock = [[NSString alloc] initWithString:@"Submit-Changes-Lock"]; } + (NSString *)submitChangesLock { return SubmitChangesLock; }

问题 I was trying to cut thread contention in my code by replacing some synchronized blocks with AtomicBoolean . Here's an example with synchronized : public void toggleCondition() { synchronized (this.mutex) { if (this.toggled) { return; } this.toggled = true; // do other stuff } } And the alternative with AtomicBoolean : public void toggleCondition() { if (!this.condition.getAndSet(true)) { // do other stuff } } Taking advantage of AtomicBoolean 's CAS property should be way faster than relying

问题 I have a Collections.synchronizedList of WeakReference, _components; I wrote something like the following, expecting the complier to complain: public boolean addComponent2(Component e) { synchronized (_components) { return _components.add(new WeakReference<Component>(e)); } } But the compiler is perfectly satisfied. Note that List.add() returns TRUE. So ok, any exit from a synchronized block releases the lock, but doesn't this LOOK strange? It's kind of like a "hole" in the block, similar to

问题 I know the difference between synchronized method and synchronized block but I am not sure about the synchronized block part. Assuming I have this code class Test { private int x=0; private Object lockObject = new Object(); public void incBlock() { synchronized(lockObject) { x++; } System.out.println("x="+x); } public void incThis() { // same as synchronized method synchronized(this) { x++; } System.out.println("x="+x); } } In this case what is the difference between using lockObject and

问题 I know the difference between synchronized method and synchronized block but I am not sure about the synchronized block part. Assuming I have this code class Test { private int x=0; private Object lockObject = new Object(); public void incBlock() { synchronized(lockObject) { x++; } System.out.println("x="+x); } public void incThis() { // same as synchronized method synchronized(this) { x++; } System.out.println("x="+x); } } In this case what is the difference between using lockObject and

问题 I know the difference between synchronized method and synchronized block but I am not sure about the synchronized block part. Assuming I have this code class Test { private int x=0; private Object lockObject = new Object(); public void incBlock() { synchronized(lockObject) { x++; } System.out.println("x="+x); } public void incThis() { // same as synchronized method synchronized(this) { x++; } System.out.println("x="+x); } } In this case what is the difference between using lockObject and