What is the difference between a StringBuffer and StringBuilder in java?

The StringBuffer and StringBuilder classes are used when there is a necessity to make a lot of modifications to Strings of characters.

• Unlike Strings, objects of type StringBuffer and String builder can be modified over and over again without leaving behind a lot of new unused objects.
• The StringBuilder class was introduced as of Java 5 and the main difference between the StringBuffer and StringBuilder is that StringBuilder’s methods are not thread safe (not synchronized).
• It is recommended to use StringBuilder whenever possible because it is faster than StringBuffer. However, if the thread safety is necessary, the best option is StringBuffer objects.