Question 16 :
What are the two basic ways in which classes that can be run as threads may be defined?
A thread class may be declared as a subclass of Thread, or it may implement the Runnable interface.
Question 17 :
What are the problems faced by Java programmers who don't use layout managers?
Without layout managers, Java programmers are faced with determining how their GUI will be displayed across multiple windowing systems and finding a common sizing and positioning that will work within the constraints imposed by each windowing system.
Question 18 :
What is the difference between an if statement and a switch statement?
The if statement is used to select among two alternatives. It uses a Boolean expression to decide which alternative should be executed. The switch statement is used to select among multiple alternatives. It uses an int expression to determine which alternative should be executed.
Question 19 :
Can there be an abstract class with no abstract methods in it?
Question 20 :
Can an Interface be final?