Difference between StringBuilder and StringBuffer

Question

What is the main difference between StringBuffer and StringBuilder? Is there any performance issues when deciding on any one of these?

Answer 1

StringBuffer is mutable. It can change in terms of length and content. StringBuffers are thread-safe, meaning that they have synchronized methods to control access so that only one thread can access a StringBuffer object's synchronized code at a time. Thus, StringBuffer objects are generally safe to use in a multi-threaded environment where multiple threads may be trying to access the same StringBuffer object at the same time.

StringBuilder The StringBuilder class is very similar to StringBuffer, except that its access is not synchronized so that it is not thread-safe. By not being synchronized, the performance of StringBuilder can be better than StringBuffer. Thus, if you are working in a single-threaded environment, using StringBuilder instead of StringBuffer may result in increased performance. This is also true of other situations such as a StringBuilder local variable (ie, a variable within a method) where only one thread will be accessing a StringBuilder object.