[android] StringBuffer에 대해서

https://developer.android.com/reference/java/lang/StringBuffer.html

A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls.

String과 비슷하지만 수정이 가능하다.

길이는 가변적이다.