a Learner questions

• Collections.synchronizedMap
• automatically interning of string literals
• Reading mails using Spring email abstraction layer
• using volatile keyword in java4 and java5
• Setting the response content-type without using HttpServletResponse
• Runtime String concatenation evaluation
• Enums, Singletons and Deserialization
• web hosting for spring and hibernate application [closed]
• spring singleton scope-- per container per bean
• string literals and permanent generation memory area

a Learner answers