Java Reference
In-Depth Information
4.
There are two types of
import
statements:
specific import
and
wildcard import
. The
specific import specifies a single class in the import statement; the wildcard import
imports all the classes in a package.
5.
In Java, the equal sign (
=
) is used as the
assignment operator.
6.
A variable declared in a method must be assigned a value before it can be used.
7.
A
named constant
(or simply a
constant
) represents permanent data that never changes.
8.
A named constant is declared by using the keyword
final
.
9.
Java provides four integer types (
byte
,
short
,
int
, and
long
) that represent integers
of four different sizes.
10.
Java provides two
floating-point types
(
float
and
double
) that represent floating-
point numbers of two different precisions.
11.
Java provides
operators
that perform numeric operations:
+
(addition),
-
(subtraction),
*
(multiplication),
/
(division), and
%
(remainder).
12.
Integer arithmetic (
/
) yields an integer result.
13.
The numeric operators in a Java expression are applied the same way as in an arithmetic
expression.
14.
Java provides the augmented assignment operators
+=
(addition assignment),
-=
(sub-
traction assignment),
*=
(multiplication assignment),
/=
(division assignment), and
%=
(remainder assignment).
15.
The
increment operator
(
++
) and the
decrement operator
(
--
) increment or decrement
a variable by
1
.
16.
When evaluating an expression with values of mixed types, Java automatically converts
the operands to appropriate types.
17.
You can explicitly convert a value from one type to another using the
(type)value
notation.
18.
Casting
a variable of a type with a small range to a variable of a type with a larger range
is known as
widening a type.
19.
Casting a variable of a type with a large range to a variable of a type with a smaller range
is known as
narrowing a type.
20.
Widening a type can be performed automatically without explicit casting. Narrowing a
type must be performed explicitly.
21.
In computer science, midnight of January 1, 1970, is known as the
UNIX epoch.
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