Japer D. questions

• java - do I have to declare my shared listener member variable as volatile?
• postgresql - java - wake up application when something in database happens
• Difference between <T extends A> void foo(T t) and void foo(A a)
• Is "ConcurrentHashMap.putAll(...)" atomic?
• Which NIO library (Netty, Grizzly, kryonet, ...) for simple backend server implementation in Java?

Japer D. answers