Interview Question for Software QA Engineer at PayPal:

Is Integer a Class or variable where can static keyword used ? Adv and Disadv of using Static variable what are things need to keep in mind when using static variable how can we apply locks static variable or how can we make sure static variable is not tamper with Java Complier and JVM - which on start first Abstract vs Interface why we need interface when abstract can do same stuff for us Can you use Interface.method?