181. To what
value is a variable of the boolean type automatically initialized?
The default value
of the boolean type is false.
182. Can try
statements be nested?
Try statements
may be tested.
183. What is the
difference between the prefix and postfix forms of the ++ operator?
The prefix form
performs the increment operation and returns the value of the increment
operation. The postfix form returns the current value all of the expression and
then performs the increment operation on that value.
184. What is the
purpose of a statement block?
A statement block
is used to organize a sequence of statements as a single statement group.
185. What is a
Java package and how is it used?
A Java package is
a naming context for classes and interfaces. A package is used to create a
separate name space for groups of classes and interfaces. Packages are also
used to organize related classes and interfaces into a single API unit and to
control accessibility to these classes and interfaces.
186. What
modifiers may be used with a top-level class?
A top-level class
may be public, abstract, or final.
187. What are the
Object and Class classes used for?
The Object class
is the highest-level class in the Java class hierarchy. The Class class is used
to represent the classes and interfaces that are loaded by a Java program..
188. How does a
try statement determine which catch clause should be used to handle an
exception?
When an exception
is thrown within the body of a try statement, the catch clauses of the try
statement are examined in the order in which they appear. The first catch
clause that is capable of handling the exception is executed. The remaining
catch clauses are ignored.
189. Can an
unreachable object become reachable again?
An unreachable
object may become reachable again. This can happen when the object's finalize()
method is invoked and the object performs an operation which causes it to
become accessible to reachable objects.
190. When is an
object subject to garbage collection?
An object is
subject to garbage collection when it becomes unreachable to the program in
which it is used.
191. What method
must be implemented by all threads?
All tasks must
implement the run() method, whether they are a subclass of Thread or
implement the Runnable interface.
192. What methods
are used to get and set the text label displayed by a Button object?
getLabel() and
setLabel()
193. Which
Component subclass is used for drawing and painting?
Canvas
194. What are
synchronized methods and synchronized statements?
Synchronized
methods are methods that are used to control access to an object. A thread only
executes a synchronized method after it has acquired the lock for the method's
object or class. Synchronized statements are similar to synchronized methods. A
synchronized statement can only be executed after a thread has acquired the
lock for the object or class referenced in the synchronized statement.
195. 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.
196. 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.
197. 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.
198. What happens
when you add a double value to a String?
The result is a
String object.
199. What is the
List interface?
The List interface provides support for ordered
collections of objects.
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