1] What is factory pattern? 2] What is singlton pattern? , how will you code it ? 3] What is a builder pattern? 4] What is Session Facade and why it is used? 5] What is Template Pattern? 6] What is service Activator Pattern?
Try Google for each of those patterns, eg "java singleton pattern", and see what you find. If the descriptions you find are confusing, ask more specific questions in the OO, UML, etc. forum further down the page.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi