CODEWITHSUNDEEP
javasynchronization
Knight Shao
Knight Shao

Reputation: 89

Access static variable in synchronized block

(Java synchronization problem)As my title, can I access a static variable in a synchronized block? Will it cause inconsistency ? Can anyone tell me the detail of the disadvantages or advantages of accessing a static variable synchronized block.

Upvotes: 0

Views: 4035

Answers (1)

AllTooSir
AllTooSir

Reputation: 49402

can I access a static variable in a synchronized block ?

Yes, You can.

Will it cause inconsistency ?

Static means shared across all the instances of that Class in a JVM. Shared resources are not thread-safe.Hence Static variables are not thread safe.So, if multiple threads tries to access a static variable, it may result in inconsistency.

The ways, which I know of to synchronize access to a static variable.

  1. Synchronize on Static object. 

       public class SomeClass{
      private static int sum = 0;
      private static final Object locker = new Object();

      public void increaseSum() {
           synchronized (locker) {
           sum++;
      }
    }
  }

  2. Synchronized Static method.

    public class SomeClass {
    private static int sum = 0;

   public static synchronized void increaseSum() {
     sum++;
 }
}

  3. Synchronize on class object

     public class SomeClass {
    private static int sum= 0;

    public void increaseSum() {
       synchronized (SomeClass .class) {
       sum++;
     }
   }
 }

Upvotes: 4

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