Java Questions

A is incorrect because classes implement interfaces, they don't extend them. B is incorrect because interfaces only "inherit from" other interfaces. D is incorrect based on the preceding rules.

The window, Frame and Dialog classes use a border layout as their default layout.

You should declared your class as final. But you can't define your class as final, if it is an abstract class. A class declared as final can't be extended by any other class.

Enumeration is twice as fast as compared to an Iterator and uses very less memory. However, the Iterator is much safer compared to Enumeration, because other threads are not able to modify the collection object that is currently traversed by the iterator. Also, Iteratorsallow the caller to remove elements from the underlying collection, something which is not possible with Enumerations.

A finally block will always be executed, whether or not an exception is actually thrown. Even in the case where the catch statement is missing and an exception is thrown, the finally block will still be executed. Last thing to mention is that the finally block is used to release resources like I/O buffers, database connections, etc.

A class can have any number of constructors. If a class have more than one constructor, we call it as the constructor is overloaded.

The Panel and Applet classes use the FlowLayout as their default layout.