Java
Career Interview Questions For Success
How can a dead thread be restarted?
A dead thread cannot be restarted.
What happens if an exception is not caught?
An uncaught exception results in the uncaughtException()
method of the thread's ThreadGroup being invoked, which eventually results
in the termination of the program in which it is thrown.
What is a layout manager?
A layout manager is an object that is used to organize
components in a container.
Which arithmetic operations can result in the throwing
of an ArithmeticException?
Integer / and % can result in the throwing of an ArithmeticException.
What are three ways in which a thread can enter the
waiting state?
A thread can enter the waiting state by invoking its
sleep() method, by blocking on I/O, by unsuccessfully attempting to acquire
an object's lock, or by invoking an object's wait() method. It can also
enter the waiting state by invoking its (deprecated) suspend() method.
Can an abstract class be final?
An abstract class may not be declared as final.
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.
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.
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.
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.
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.
To what value is a variable of the boolean type automatically
initialized?
The default value of the boolean type is false.
Can try statements be nested?
Try statements may be tested.
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.
What is the purpose of a statement block?
A statement block is used to organize a sequence of statements
as a single statement group.
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.
What modifiers may be used with a top-level class?
A top-level class may be public, abstract, or final.
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.
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.
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.
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.
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.
Which Component subclass is used for drawing and painting?
Canvas
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.
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.
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.
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.
What is the List interface?
The List interface provides support for ordered collections
of objects.
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