java synchronized example

Java has the following methods to handle concurrent access to code blocks:First, the keyword synchronizedSecond, lock (Lock Object, condition object)Java provides an internal lock for each object. After the keyword synchronized is added to the method definition, the object lock will protect the entire method. That is to say, the following two statements are equiv

To illustrate the thread synchronization problem, we must first describe the two features of Java threads, visibility and orderliness. Data Interaction cannot be directly transmitted between multiple threads. Interaction between threads can only be achieved through shared variables. The example in the previous blog shows that an object of the Count class is shared among multiple threads. This object is crea

: String S = "hello ";System. Out. println (S. hashcode ());S = "world ";System. Out. println (S. hashcode ()); In the above Code. The hashcode value of the first s is different from that of the second after the second value is assigned. Because you do not need to use new to create a string-type instance, do not assign values to this variable when synchronizing string-type variables. Otherwise, the variables cannot be synchronized. Sin

Http://www.infoq.com/cn/articles/java-memory-model-5 deep understanding of the Java Memory Model (v)--lock Http://www.ibm.com/developerworks/cn/java/j-jtp10264/Java Theory and Practice: a more flexible and scalable locking mechanism in JDK 5.0 http://blog.csdn.net/ghsau/article/details/7481142 1,

synchronous mutex access, which means that our shared resources can only be used by one thread at a time, and once that resource is used by the thread, other threads will not have the use rights. In Java, there are two ways to achieve synchronous mutex access: synchronized and lock.second, mutually exclusive access to the synchronized (synchronous method or sync

value of the hashcode of the first S and re-assigned S is not the same. Since the creation of an instance of the string class does not require the use of new, it is important to be careful not to assign a value to this variable when synchronizing a variable of type string, otherwise the variable cannot be synchronized.Since a new instance has been created for sync on line 012, assuming that method1 executes first, when the Method1 method executes 013 lines of code, the value of sync is not the

which point the thread B may get the time to execute the code in that object. However, it can only execute non-synchronous code (not decorated with synchronized), when executed to the synchronization code, it will be blocked, the thread planner may also let a thread run, a thread continues to hold an object-level lock, when a thread exits the synchronization code (that is, the release of the object-level lock), if the B-thread is run again , the obje

Previous Article: Java thread (1) In the previous article, we used a simple example to illustrate the thread security and insecurity. In this example, the output results are incremental one by one due to the insecurity. Why does this happen, because the created count object is shared by threads, a thread changes its member variable num value, and the next thread

, the method returns immediately, and if you need to use a value computed by this thread after calling the Start method, you must use the Join method. If you do not use the Join method, you cannot guarantee that the thread will run out when a statement after the Start method is executed. After the Join method is used, the program does not go down until the thread exits. public class Jointhread extends Thread {public static int n = 0; Static synchronized