TIOBE - Java Coding Standard

Rule: StringandStringBuffer11

Synopsis:	Initialize objects of StringBuffer with a proper size
Language:	Java
Severity Level:	8
Category:	StringandStringBuffer

Description:

Failing to pre-size a StringBuffer properly could cause it to re-size many times during runtime. This rule checks the characters that are actually passed into StringBuffer.append(), but represents a best guess "worst case" scenario. An empty StringBuffer constructor initializes the object to 16 characters. This default is assumed if the length of the constructor can not be determined.

public class Foo {
    void bar() {
        StringBuffer bad = new StringBuffer();
        bad.append("This is a long string, will exceed the default 16 characters");//bad 
        StringBuffer good = new StringBuffer(41);
        good.append("This is a long string, which is pre-sized");//good
    }
}