1、String
final modification, immutable
String takes more time than the same thread is 25 times the StringBuffer 7500ms
2、StringBuffer
Final decoration, variable, thread-safe, check the jdk source code can be found that most of the methods are synchronized (synchronous code block) decoration
StringBuffer takes less time
3.StringBuider is 0.5 times the StringBuilder under the same thread 300ms
final decoration, variable, thread unsafe, no synchronized decoration
StringBuilder usage time is at least 250ms