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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.
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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.
-
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.
-
What is the argument type of a
program’s main() method? - A
program’s main() method takes an
argument of the String[] type.
-
Which Java operator is right
associative? - The = operator is
right associative.
-
Can a double value be cast to a
byte? - Yes, a double value can
be cast to a byte.
-
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.
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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.
-
What is the advantage of the
event-delegation model over the
earlier event-inheritance 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.
-
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.
-
What is an abstract method? -
An abstract method is a method whose
implementation is deferred to a
subclass.
-
What value does read() return
when it has reached the end of a
file? - The read() method
returns -1 when it has reached the
end of a file.
-
Can a Byte object be cast to a
double value? - No, an object
cannot be cast to a primitive value.
-
What is the difference between a
static and a non-static inner class?
- A non-static inner class may have
object instances that are associated
with instances of the class’s outer
class. A static inner class does not
have any object instances.
-
If a variable is declared as
private, where may the variable be
accessed? - A private variable
may only be accessed within the
class in which it is declared.
-
What is an object’s lock and
which object’s have locks? - An
object’s lock is a mechanism that is
used by multiple threads to obtain
synchronized access to the object. A
thread may execute a synchronized
method of an object only after it
has acquired the object’s lock. All
objects and classes have locks. A
class’s lock is acquired on the
class’s Class object.
-
What is the % operator? - It
is referred to as the modulo or
remainder operator. It returns the
remainder of dividing the first
operand by the second operand.
-
When can an object reference be
cast to an interface reference?
- An object reference be cast to an
interface reference when the object
implements the referenced interface.
-
Which class is extended by all
other classes? - The Object
class is extended by all other
classes.
-
Can an object be garbage
collected while it is still
reachable? - A reachable object
cannot be garbage collected. Only
unreachable objects may be garbage
collected.
-
Is the ternary operator written x
: y ? z or x ? y : z ? - It is
written x ? y : z.
-
How is rounding performed under
integer division? - The
fractional part of the result is
truncated. This is known as rounding
toward zero.
-
What is the difference between
the Reader/Writer class hierarchy
and the InputStream/OutputStream
class hierarchy? - The
Reader/Writer class hierarchy is
character-oriented, and the
InputStream/OutputStream class
hierarchy is byte-oriented.
-
What classes of exceptions may be
caught by a catch clause? - A
catch clause can catch any exception
that may be assigned to the
Throwable type. This includes the
Error and Exception types.
-
If a class is declared without
any access modifiers, where may the
class be accessed? - A class
that is declared without any access
modifiers is said to have package
access. This means that the class
can only be accessed by other
classes and interfaces that are
defined within the same package.
-
Does a class inherit the
constructors of its superclass?
- A class does not inherit
constructors from any of its
superclasses.
-
What is the purpose of the System
class? - The purpose of the
System class is to provide access to
system resources.
-
Name the eight primitive Java
types. - The eight primitive
types are byte, char, short, int,
long, float, double, and boolean.
-
Which class should you use to
obtain design information about an
object? - The Class class is
used to obtain information about an
object’s design.