Given this method in a class: 21. public String toString() { 22. StringBuffer buffer = new StringBuffer(); 23. buffer.append(''); 26. return buffer.toString(); 27. } Which statement is true?
This code is NOT thread-safe
The programmer can replace StringBuffer with StringBuilder with no other changes
This code will perform poorly. For better performance, the code should be rewritten:return "";
This code will perform well and converting the code to use StringBuilder will not enhance the performance