String, StringBuffer, and StringBuilder

Question

Please tell me a real time situation to compare String, StringBuffer, and StringBuilder?

Answer 1

• You use String when an immutable structure is appropriate; obtaining a new character sequence from a String may carry an unacceptable performance penalty, either in CPU time or memory (obtaining substrings is CPU efficient because the data is not copied, but this means a potentially much larger amount of data may remain allocated).
• You use StringBuilder when you need to create a mutable character sequence, usually to concatenate several character sequences together.
• You use StringBuffer in the same circumstances you would use StringBuilder, but when changes to the underlying string must be synchronized (because several threads are reading/modifyind the string buffer).

See an example here.