为什么Java的SimpleDateFormat不是线程安全的？ [重复] - Why is Java's SimpleDateFormat not thread-safe? [duplicate]

问题：

This question already has an answer here: 这个问题在这里已有答案：

• “Java DateFormat is not threadsafe” what does this leads to? “Java DateFormat不是线程安全的”这会导致什么？ 10 answers 10个答案

Please tell with a code example why is SimpleDateFormat not threadsafe. 请告诉代码示例为什么SimpleDateFormat不是线程安全的。 What is the problem in this class? 这堂课有什么问题？ Is The problem with format function of SimpleDateFormat ? SimpleDateFormat的格式功能有问题吗？ Please give a code which demonstrates this fault in class. 请给出一个在课堂上演示此错误的代码。

FastDateFormat is threadsafe. FastDateFormat是线程安全的。 Why? 为什么？ what is the difference b/w the SimpleDateFormat and FastDateFormat? b / w SimpleDateFormat和FastDateFormat有什么区别？

Please explain with a code which demonstrates this issue? 请用解释此问题的代码解释一下？

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解决方案：

参考一： https://stackoom.com/question/ShbX
参考二： Why is Java's SimpleDateFormat not thread-safe? [duplicate]