Where to use StringBuffer/StringBuilder than String [duplicate]

Question

Possible Duplicate:
String, StringBuffer, and StringBuilder

We know that String are immutable where StringBuffer/StringBuilder are mutable. But sometimes we get confused what to use in our code.. the String or StringBuffer/StringBuilder ?? Practically in our maximum code/quick code we use to prefer String than StringBuffer/StringBuilder.

This question is to solve the confusion, if you have any idea & proper reason for that, then please give a reply.

Answer 1

Below is the main difference between these three most commonly used classes.

• String class objects are immutable whereas StringBuffer and StringBuilder objects are mutable.
• StringBuffer is synchronized while StringBuilder is not synchronized.
• Concatenation operator "+" is internal implemented using either StringBuffer or StringBuilder.

Criteria to choose among String, StringBuffer and StringBuilder

• If the Object value is not going to change use String Class because a String object is immutable.
• If the Object value can change and will only be accessed from a single thread, use a StringBuilder because StringBuilder is unsynchronized.
• In case the Object value can change, and will be modified by multiple threads, use a StringBuffer because StringBuffer is synchronized.