StringBuffer and StringBuilder former is thread-safe which is thread safe, during the encoding priority use StringBuilder if you do not consider under multiple threads or thread-safe, because the execution faster!
1.String StringBuffer, StringBuilder three contrast,
1.String: immutable sequence of characters; underlayer using char [] storage
2.StringBuffer: variable sequence of characters; thread-safe, low efficiency; underlayer using char [] storage
3.StringBuilder: variable sequence of characters; JDK5.0 new, thread-safe, high efficiency; underlayer using char [] storage
4. efficiency: StringBuilder> StringBuffer> String
2.StringBuffer, StringBuilder methods commonly used
By: append (xxx)
Delete: delete (int start, int end )
change: setCharAt (int n, char ch ) / replace (int start, int end, String str)
check: charAt (int n)
is inserted: insert (int offset, xxx)