访问同步块中的静态变量 [英] Access static variable in synchronized block

问题描述

(Java同步问题)作为我的标题，我可以在同步块中访问静态变量吗?会导致不一致吗?谁能告诉我访问静态变量同步块的优缺点的详细信息.

(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.

推荐答案

我可以访问同步块中的静态变量吗?

是的，你可以.

会导致不一致吗?

静态意味着在 JVM 中该类的所有实例之间共享.共享资源不是线程安全的.因此静态变量不是线程安全的.因此，如果多个线程试图访问一个静态变量，可能会导致不一致.

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.

我所知道的同步访问静态变量的方法.

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

1. 同步静态对象.

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++;
      }
    }
  }

同步静态方法.

Synchronized Static method.

public class SomeClass {
    private static int sum = 0;

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

在类对象上同步

Synchronize on class object

 public class SomeClass {
    private static int sum= 0;

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

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