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Java Interview Questions
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Java, the language, is a high-level object-oriented programming language, influenced in various ways by C, C++, and Smalltalk, with ideas borrowed from other languages as well (see O'Reilly's History of Programming Languages). Its syntax was designed to be familiar to those familiar with C-descended "curly brace" languages, but with arguably stronger OO principles than those found in C++, static typing of objects, and a fairly rigid system of exceptions that require every method in the call stack to either handle exceptions or declare their ability to throw them. Garbage collection is assumed, sparing the developer from having to free memory used by obsolete objects.
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Java FAQs - 1 |
Java FAQs - 2 |
Java FAQs - 3 |
Java FAQs - 4 |
Java FAQs - 5
Java FAQs - 6 |
Java FAQs - 7 |
Java FAQs - 8 |
Java FAQs - 9 |
Java FAQs - 10
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Core Java Interview Questions - Part10
176. What is the ResourceBundle class?
The ResourceBundle class is used to store locale-specific resources that can be
loaded by
a program to tailor the program's appearance to the particular locale in which
it is being
run.
177. What happens if a try-catch-finally statement does not have a catch clause
to handle
an exception that is thrown within the body of the try statement?
The exception propagates up to the next higher level try-catch statement (if
any) or
results in the program's termination.
178. What is numeric promotion?
Numeric promotion is the conversion of a smaller numeric type to a larger
numeric type,
so that integer and floating-point operations may take place. In numerical
promotion,
byte, char, and short values are converted to int values. The int values are
also converted
to long values, if necessary. The long and float values are converted to double
values, as
required.
179. What is the difference between a Scrollbar and a ScrollPane?
A Scrollbar is a Component, but not a Container. A ScrollPane is a Container. A
ScrollPane handles its own events and performs its own scrolling.
180. What is the difference between a public and a non-public class?
A public class may be accessed outside of its package. A non-public class may
not be
accessed outside of its package.
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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