> For the complete documentation index, see [llms.txt](https://heunnajo.gitbook.io/java/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://heunnajo.gitbook.io/java/java.lang-package-and-useful-class/stringbuilder-class.md).

# StringBuilder class

\- StringBuffer와 비슷하다. 하지만 StringBuffer는 동기화되어있어서 멀티쓰레드에 안전하지만(thread-safe)\
\- StringBuilder는 동기화되어있지 않아서 멀티쓰레드에 안전하지 않다.\
\- 멀티 쓰레드 프로그램이 아닌 경우, 동기화는 불필요한 성능저하를 유발한다.\
\=> 싱글 쓰레드 프로그램인 경우, StringBuilder를 사용하면 성능 향상.

* 동기화 : 데이터를 보호하는 것. 멀티스레드는 n개의 작업을 동시에 하는데, 이 때 데이터를 공유하게 된다. 여러 작업을 동시에 할 때 데이터가 꼬이지 않도록 하는 것이 동기화이다.


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