Java Reference
In-Depth Information
9
.
In Java, the logical operators are
!
(
not
),
&&
(
and
), and
||
(
or
).
10
.
In Java, there are three selection structures.
11
.
One-way selection takes the following form:
if
(logical expression)
statement
If
logical expression
is
true
, then the
statement
executes; otherwise,
the computer executes the statement following the
if
statement.
12
.
Two-way selection takes the following form:
4
if
(logical expression)
statement1
else
statement2
If
logical expression
is
true
, then
statement1
executes; otherwise,
statement2
executes.
13
.
The expression in an
if
or
if
...
else
structure is a logical expression.
14
.
Including a semicolon before the
statement
in a one-way selection creates
a semantic error. In this case, the action of the
if
statement is empty.
15
.
Including a semicolon before
statement1
in a two-way selection creates a
syntax error.
16
.
There is no stand-alone
else
statement in Java. Every
else
has a related
if
.
17
.
An
else
is paired with the most recent
if
that has not been paired with
any other
else
.
18
.
A sequence of statements enclosed between braces,
{
and
}
, is called a
compound statement or block of statements. A compound statement is
treated as a single statement.
19
.
A
switch
structure is used to handle multiple selections.
20
.
The
expression
in a
switch
statement must evaluate to an integral value.
21
.
A
switch
statement executes according to the following rules:
a.
When the value of the
expression
is matched against a
case
value,
the statements execute until either a
break
statement is found or the
end of the
switch
structure is reached.
b.
If the value of the
expression
does not match any of the
case
values,
the statements following the
default
label execute. If the
switch
structure has no
default
label, and if the value of the
expression
does
not match any of the
case
values, the entire
switch
statement is skipped.
c.
A
break
statement causes an immediate exit from the
switch
structure.
22
.
To compare strings, you use the method
compareTo
of the
class
String
.
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