java - 线程安全的程序如何包含非线程安全的类？

Question

我刚开始阅读 Java Concurrency in Practice , 从第 17 页开始:

We’ve used the terms “thread-safe class” and “thread-safe program” nearly interchangeably thus far. Is a thread-safe program one that is constructed entirely of thread-safe classes? Not necessarily—a program that consists entirely of thread-safe classes may not be thread-safe, and a thread-safe program may contain classes that are not thread-safe.

• 线程安全的程序如何包含非线程安全的类？非常感谢额外的代码示例。

Answer 1

有两种可能的基本情况:

1. 非线程安全对象仅限于单个线程。

2. 对共享的非线程安全对象的访问由使用它们的线程进行外部协调。极其简单的例子:通过同步所有访问
   

       synchronized( sharedObject ) {
           sharedObject.access();
       }