lexin2046的专栏

1. Do i need to create a new exception class ?     When faced with choosing the type of exception to throw, you can either use one written by someone else — the Java platform provides a lot of exce

1. Factory method should be stateless. State normally refers to the member variables of class. Stateless, more precisely, it means immutable. Factory is just to create objects, and one call shou

1. Configure log4j on package level When you want the logs for different package to be in different log files, you can configure log4j in package level. So Log4j can be configured on package level