Java Reference
In-Depth Information
14.
3, 4,
3.0, 3.0,
4.0,
and
4.0
15.
roundedAnswer = (
int
)Math.round(answer);
16.
long
. Because one argument is of type long, the int argument is automatically type
cast to
long
.
17. They are all legal.
18. An object of the class
Double
; the assignment is equivalent to
Double price =
new
Double(1.99);
19. A value of the primitive type
int
; the assignment is equivalent to
int
count = (
new
Integer(12)).intValue();
20.
Objects are Not equal.
21.
Double.toString(result)
22.
Double.parseDouble(stringForm)
23.
Double.parseDouble(stringForm.trim())
24.
System.out.println("Largest long is" + Long.MAX_VALUE +
"Smallest long is" + Long.MIN_VALUE);
25.
Character zeeObject =
new
Character('Z');
26. No, none of the wrapper classes discussed in this chapter have no-argument
constructors.
27. A
reference type
is a type whose variables contain references, that is, memory
addresses. Class types are reference types. Primitive types are not reference types.
28. When comparing two objects of a class type, you should use the method
equals
.
29. When comparing two objects of a primitive type, you should you use
==
.
30. Yes, a method with an argument of a class type can change the values of the instance
variables in the object named by the argument.
31. No, a method cannot change the value of an
int
variable given as an argument to
the method.
32. The variable
anObject
names no object, so the invocation of the
set
method is
an error. One way to fix things is as follows:
ToyClass anObject =
new
ToyClass();
anObject.set("Josephine", 42);
33. The constant
null
can be assigned to a variable of any class type. It does not really
have a type, but you can think of its type as being the type of a memory address.
You can also think of
null
as being of every class type.