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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 - Part5
51. What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to
perform
any cleanup processing before the object is garbage collected.
52. Which class is the immediate superclass of the MenuComponent class.
Object
53. What invokes a thread's run() method?
After a thread is started, via its start() method or that of the Thread class,
the JVM
invokes the thread's run() method when the thread is initially executed.
54. What is the difference between the Boolean & operator and the &&
operator?
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.
55. Name three subclasses of the Component class.
Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar,
or
TextComponent
56. What is the GregorianCalendar class?
The GregorianCalendar provides support for traditional Western calendars.
57. Which Container method is used to cause a container to be laid out and
redisplayed?
validate()
58. What is the purpose of the Runtime class?
The purpose of the Runtime class is to provide access to the Java runtime
system.
59. How many times may an object's finalize() method be invoked by the
garbage collector?
An object's finalize() method may only be invoked once by the garbage collector.
60. What is the purpose of the finally clause of a try-catch-finally statement?
The finally clause is used to provide the capability to execute code no matter
whether or
not an exception is thrown or caught.
61. What is the argument type of a program's main() method?
A program's main() method takes an argument of the String[] type.
62. Which Java operator is right associative?
The = operator is right associative.
63. What is the Locale class?
The Locale class is used to tailor program output to the conventions of a
particular
geographic, political, or cultural region.
64. Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.
65. What is the difference between a break statement and a continue statement?
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.
66. What must a class do to implement an interface?
It must provide all of the methods in the interface and identify the interface
in its
implements clause.
67. What method is invoked to cause an object to begin executing as a separate
thread?
The start() method of the Thread class is invoked to cause an object to begin
executing as
a separate thread.
68. Name two subclasses of the TextComponent class.
TextField and TextArea
69. What is the advantage of the event-delegation model over the earlier
eventinheritance
model?
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.
70. Which containers may have a MenuBar?
Frame
71. How are commas used in the intialization and iteration parts of a for
statement?
Commas are used to separate multiple statements within the initialization and
iteration
parts of a for statement.
72. What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient
way for
threads to wait for a shared resource. When a thread executes an object's wait()
method, it
enters the waiting state. It only enters the ready state after another thread
invokes the
object's notify() or notifyAll() methods..
73. What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass.
74. How are Java source code files named?
A Java source code file takes the name of a public class or interface that is
defined within
the file. A source code file may contain at most one public class or interface.
If a public
class or interface is defined within a source code file, then the source code
file must take
the name of the public class or interface. If no public class or interface is
defined within a
source code file, then the file must take on a name that is different than its
classes and
interfaces. Source code files use the .java extension.
75. What is the relationship between the Canvas class and the Graphics class?
A Canvas object provides access to a Graphics object via its paint() method.
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