CORE JAVA FREQUENTLY ASKED QUESTIONS AND ANSWERS-4
Question: Can an anonymous class be declared as implementing an interface and extending a class?
Answer: An anonymous class may implement an interface or extend a superclass, but may not be declared to do both.
Question: What is the range of the char type?
Answer: The range of the char type is 0 to 2^16 - 1.
Question: What is the purpose of finalization?
Answer: The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.
Question: What is the difference between the Boolean & operator and the && operator?
Answer: If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.
Question: How many times may an object's finalize() method be invoked by the garbage collector?
Answer: An object's finalize() method may only be invoked once by the garbage collector.
Question: What is the purpose of the finally clause of a try-catch-finally statement?
Answer: The finally clause is used to provide the capability to execute code no matter whether or not an exception is thrown or caught.
Question: What is the argument type of a program's main() method?
Answer: A program's main() method takes an argument of the String[] type.
Question: Which Java operator is right associative?
Answer: The = operator is right associative.
Question: Can a double value be cast to a byte?
Answer: Yes, a double value can be cast to a byte.
Question: What is the difference between a break statement and a continue statement?
Answer: A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.
Question: What must a class do to implement an interface?
Answer: It must provide all of the methods in the interface and identify the interface in its implements clause.
Question: What is the advantage of the event-delegation model over the earlier event-inheritance model?
Answer: The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a component's design and its use. The other advantage of the event-delegation model is that it performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to repeatedly process unhandled events, as is the case of the event-inheritance model.
Question: How are commas used in the intialization and iteration parts of a for statement?
Answer: Commas are used to separate multiple statements within the initialization and iteration parts of a for statement.
Question: What is an abstract method?
Answer: An abstract method is a method whose implementation is deferred to a subclass.
Question: What value does read() return when it has reached the end of a file?
Answer: The read() method returns -1 when it has reached the end of a file.