<s>
In	O
the	O
Java	B-Language
programming	I-Language
language	I-Language
,	O
a	O
keyword	O
is	O
any	O
one	O
of	O
67	O
reserved	O
words	O
that	O
have	O
a	O
predefined	O
meaning	O
in	O
the	O
language	O
.	O
</s>
<s>
Because	O
of	O
this	B-Application
,	O
programmers	O
cannot	O
use	O
keywords	O
in	O
some	O
contexts	O
,	O
such	O
as	O
names	O
for	B-Language
variables	O
,	O
methods	B-Language
,	O
classes	O
,	O
or	O
as	O
any	O
other	O
identifier	O
.	O
</s>
<s>
Due	O
to	O
their	O
special	O
functions	O
in	O
the	O
language	O
,	O
most	O
integrated	B-Application
development	I-Application
environments	I-Application
for	B-Language
Java	B-Language
use	O
syntax	O
highlighting	O
to	O
display	O
keywords	O
in	O
a	O
different	O
colour	O
for	B-Language
easy	O
identification	O
.	O
</s>
<s>
Added	O
in	O
Java	B-Language
9	O
,	O
the	O
underscore	O
has	O
become	O
a	O
keyword	O
and	O
cannot	O
be	O
used	O
as	O
a	O
variable	O
name	O
anymore	O
.	O
</s>
<s>
Abstract	O
methods	B-Language
must	O
be	O
implemented	O
in	O
the	O
sub	O
classes	O
.	O
</s>
<s>
Assert	O
describes	O
a	O
predicate	O
(	O
a	O
true	O
–	O
false	O
statement	O
)	O
placed	O
in	O
a	O
Java	B-Language
program	O
to	O
indicate	O
that	O
the	O
developer	O
thinks	O
that	O
the	O
predicate	O
is	O
always	O
true	O
at	O
that	O
place	O
.	O
</s>
<s>
Defines	O
a	O
boolean	O
variable	O
for	B-Language
the	O
values	O
"	O
true	O
"	O
or	O
"	O
false	O
"	O
only	O
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
boolean	O
.	O
</s>
<s>
The	O
byte	B-Application
keyword	O
is	O
used	O
to	O
declare	O
a	O
field	O
that	O
can	O
hold	O
an	O
8-bit	O
signed	O
two	O
's	O
complement	O
integer	O
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
byte	B-Application
.	O
</s>
<s>
Defines	O
a	O
character	O
variable	O
capable	O
of	O
holding	O
any	O
character	O
of	O
the	O
java	B-Language
source	O
file	O
's	O
character	O
set	O
.	O
</s>
<s>
A	O
class	O
definition	O
defines	O
instance	O
and	O
class	O
fields	B-Application
,	O
methods	B-Language
,	O
and	O
inner	O
classes	O
as	O
well	O
as	O
specifying	O
the	O
interfaces	B-Language
the	O
class	O
implements	B-Language
and	O
the	O
immediate	O
superclass	O
of	O
the	O
class	O
.	O
</s>
<s>
For	B-Language
example	O
,	O
String.class	O
can	O
be	O
used	O
instead	O
of	O
doing	O
new	O
String( )	O
.getClass( )	O
.	O
</s>
<s>
Alternatively	O
,	O
the	O
default	O
keyword	O
can	O
also	O
be	O
used	O
to	O
declare	O
default	O
values	O
in	O
a	O
Java	B-Language
annotation	I-Language
.	O
</s>
<s>
From	O
Java	B-Language
8	O
onwards	O
,	O
the	O
default	O
keyword	O
can	O
be	O
used	O
to	O
allow	O
an	O
interface	B-Language
to	O
provide	O
an	O
implementation	O
of	O
a	O
method	O
.	O
</s>
<s>
If	O
the	O
expression	O
evaluates	O
to	O
true	O
,	O
the	O
block	O
is	O
executed	O
again	O
;	O
this	B-Application
continues	O
until	O
the	O
expression	O
evaluates	O
to	O
false	O
.	O
</s>
<s>
The	O
double	O
keyword	O
is	O
used	O
to	O
declare	O
a	O
variable	O
that	O
can	O
hold	O
a	O
64-bit	O
double	O
precision	O
IEEE	O
754	O
floating-point	B-Algorithm
number	I-Algorithm
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
double	O
.	O
</s>
<s>
The	O
else	B-Language
keyword	O
is	O
used	O
in	O
conjunction	O
with	O
if	O
to	O
create	O
an	O
if-else	B-Language
statement	I-Language
,	O
which	O
tests	O
a	O
boolean	O
expression	O
;	O
if	O
the	O
expression	O
evaluates	O
to	O
true	O
,	O
the	O
block	O
of	O
statements	O
associated	O
with	O
the	O
if	O
are	O
evaluated	O
;	O
if	O
it	O
evaluates	O
to	O
false	O
,	O
the	O
block	O
of	O
statements	O
associated	O
with	O
the	O
else	B-Language
are	O
evaluated	O
.	O
</s>
<s>
A	O
Java	B-Language
keyword	O
used	O
to	O
declare	O
an	O
enumerated	B-Language
type	I-Language
.	O
</s>
<s>
Enumerations	B-Language
extend	O
the	O
base	O
class	O
.	O
</s>
<s>
Used	O
in	O
a	O
class	O
declaration	O
to	O
specify	O
the	O
superclass	O
;	O
used	O
in	O
an	O
interface	B-Language
declaration	O
to	O
specify	O
one	O
or	O
more	O
superinterfaces	O
.	O
</s>
<s>
Class	O
X	O
extends	B-Language
class	O
Y	O
to	O
add	O
functionality	O
,	O
either	O
by	O
adding	O
fields	B-Application
or	O
methods	B-Language
to	O
class	O
Y	O
,	O
or	O
by	O
overriding	B-Language
methods	B-Language
of	O
class	O
Y	O
.	O
</s>
<s>
An	O
interface	B-Language
Z	O
extends	B-Language
one	O
or	O
more	O
interfaces	B-Language
by	O
adding	O
methods	B-Language
.	O
</s>
<s>
Class	O
X	O
is	O
said	O
to	O
be	O
a	O
subclass	O
of	O
class	O
Y	O
;	O
Interface	B-Language
Z	O
is	O
said	O
to	O
be	O
a	O
subinterface	B-Application
of	O
the	O
interfaces	B-Language
it	O
extends	B-Language
.	O
</s>
<s>
More	O
specifically	O
:	O
a	O
final	B-Language
class	O
cannot	O
be	O
subclassed	O
,	O
a	O
final	B-Language
method	I-Language
cannot	O
be	O
overridden	B-Language
,	O
and	O
a	O
final	B-Language
variable	O
can	O
occur	O
at	O
most	O
once	O
as	O
a	O
left-hand	O
expression	O
on	O
an	O
executed	O
command	O
.	O
</s>
<s>
All	O
methods	B-Language
in	O
a	O
final	B-Language
class	O
are	O
implicitly	O
final	B-Language
.	O
</s>
<s>
Used	O
to	O
define	O
a	O
block	O
of	O
statements	O
for	B-Language
a	O
block	O
defined	O
previously	O
by	O
the	O
try	O
keyword	O
.	O
</s>
<s>
The	O
finally	O
block	O
is	O
executed	O
after	O
execution	O
exits	O
the	O
try	O
block	O
and	O
any	O
associated	O
catch	O
clauses	O
regardless	O
of	O
whether	O
an	O
exception	O
was	O
thrown	O
or	O
caught	O
,	O
or	O
execution	O
left	O
method	O
in	O
the	O
middle	O
of	O
the	O
try	O
or	O
catch	O
blocks	O
using	O
the	O
return	B-Language
keyword	O
.	O
</s>
<s>
The	O
float	B-Algorithm
keyword	O
is	O
used	O
to	O
declare	O
a	O
variable	O
that	O
can	O
hold	O
a	O
32-bit	O
single	O
precision	O
IEEE	O
754	O
floating-point	B-Algorithm
number	I-Algorithm
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
float	B-Algorithm
.	O
</s>
<s>
The	O
for	B-Language
keyword	O
is	O
used	O
to	O
create	O
a	O
for	B-Language
loop	I-Language
,	O
which	O
specifies	O
a	O
variable	O
initialization	O
,	O
a	O
boolean	O
expression	O
,	O
and	O
an	O
incrementation	O
.	O
</s>
<s>
The	O
boolean	O
expression	O
is	O
then	O
evaluated	O
again	O
;	O
this	B-Application
continues	O
until	O
the	O
expression	O
evaluates	O
to	O
false	O
.	O
</s>
<s>
As	O
of	O
J2SE	O
5.0	O
,	O
the	O
for	B-Language
keyword	O
can	O
also	O
be	O
used	O
to	O
create	O
a	O
so-called	O
"	O
enhanced	O
for	B-Language
loop	I-Language
"	O
,	O
which	O
specifies	O
an	O
array	O
or	O
object	O
;	O
each	O
iteration	O
of	O
the	O
loop	O
executes	O
the	O
associated	O
block	O
of	O
statements	O
using	O
a	O
different	O
element	O
in	O
the	O
array	O
or	O
Iterable	O
.	O
</s>
<s>
This	B-Application
keyword	O
can	O
also	O
be	O
used	O
to	O
create	O
an	O
if-else	B-Language
statement	I-Language
;	O
see	O
else	B-Language
.	O
</s>
<s>
Included	O
in	O
a	O
class	O
declaration	O
to	O
specify	O
one	O
or	O
more	O
interfaces	B-Language
that	O
are	O
implemented	O
by	O
the	O
current	O
class	O
.	O
</s>
<s>
A	O
class	O
inherits	O
the	O
types	O
and	O
abstract	O
methods	B-Language
declared	O
by	O
the	O
interfaces	B-Language
.	O
</s>
<s>
Used	O
at	O
the	O
beginning	O
of	O
a	O
source	O
file	O
to	O
specify	O
classes	O
or	O
entire	O
Java	B-Language
packages	I-Language
to	O
be	O
referred	O
to	O
later	O
without	O
including	O
their	O
package	B-Language
names	O
in	O
the	O
reference	O
.	O
</s>
<s>
Since	O
J2SE	O
5.0	O
,	O
import	O
statements	O
can	O
import	O
static	B-General_Concept
members	O
of	O
a	O
class	O
.	O
</s>
<s>
A	O
binary	O
operator	O
that	O
takes	O
an	O
object	O
reference	O
as	O
its	O
first	O
operand	O
and	O
a	O
class	O
or	O
interface	B-Language
as	O
its	O
second	O
operand	O
and	O
produces	O
a	O
boolean	O
result	O
.	O
</s>
<s>
The	O
instanceof	O
operator	O
evaluates	O
to	O
true	O
if	O
and	O
only	O
if	O
the	O
runtime	O
type	O
of	O
the	O
object	O
is	O
assignment	O
compatible	O
with	O
the	O
class	O
or	O
interface	B-Language
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
int	O
.	O
</s>
<s>
Used	O
to	O
declare	O
a	O
special	O
type	O
of	O
class	O
that	O
only	O
contains	O
abstract	O
or	O
default	O
methods	B-Language
,	O
constant	O
(	O
static	B-General_Concept
final	B-Language
)	O
fields	B-Application
and	O
static	B-General_Concept
interfaces	B-Language
.	O
</s>
<s>
It	O
can	O
later	O
be	O
implemented	O
by	O
classes	O
that	O
declare	O
the	O
interface	B-Language
with	O
the	O
implements	B-Language
keyword	O
.	O
</s>
<s>
As	O
multiple	B-Application
inheritance	I-Application
is	O
not	O
allowed	O
in	O
Java	B-Language
,	O
interfaces	B-Language
are	O
used	O
to	O
circumvent	O
it	O
.	O
</s>
<s>
An	O
interface	B-Language
can	O
be	O
defined	O
within	O
another	O
interface	B-Language
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
long	O
.	O
</s>
<s>
Used	O
in	O
method	O
declarations	O
to	O
specify	O
that	O
the	O
method	O
is	O
not	O
implemented	O
in	O
the	O
same	O
Java	B-Language
source	O
file	O
,	O
but	O
rather	O
in	O
another	O
language	O
.	O
</s>
<s>
Using	O
keyword	O
for	B-Language
this	B-Application
end	O
is	O
not	O
completely	O
necessary	O
(	O
as	O
exemplified	O
by	O
Scala	B-Application
)	O
,	O
though	O
it	O
serves	O
two	O
purposes	O
:	O
it	O
enables	O
the	O
existence	O
of	O
different	O
namespace	O
for	B-Language
methods	B-Language
and	O
class	O
names	O
,	O
it	O
defines	O
statically	O
and	O
locally	O
that	O
a	O
fresh	O
object	O
is	O
indeed	O
created	O
,	O
and	O
of	O
what	O
runtime	O
type	O
it	O
is	O
(	O
arguably	O
introducing	O
dependency	O
into	O
the	O
code	O
)	O
.	O
</s>
<s>
Java	B-Language
package	I-Language
is	O
a	O
group	O
of	O
similar	O
classes	O
and	O
interfaces	B-Language
.	O
</s>
<s>
Packages	O
are	O
declared	O
with	O
the	O
package	B-Language
keyword	O
.	O
</s>
<s>
The	O
private	O
keyword	O
is	O
used	O
in	O
the	O
declaration	O
of	O
a	O
method	O
,	O
field	O
,	O
or	O
inner	B-Language
class	I-Language
;	O
private	O
members	O
can	O
only	O
be	O
accessed	O
by	O
other	O
members	O
of	O
their	O
own	O
class	O
.	O
</s>
<s>
The	O
protected	O
keyword	O
is	O
used	O
in	O
the	O
declaration	O
of	O
a	O
method	O
,	O
field	O
,	O
or	O
inner	B-Language
class	I-Language
;	O
protected	O
members	O
can	O
only	O
be	O
accessed	O
by	O
members	O
of	O
their	O
own	O
class	O
,	O
that	O
class	O
's	O
subclasses	B-Language
or	O
classes	O
from	O
the	O
same	O
package	B-Language
.	O
</s>
<s>
The	O
public	O
keyword	O
is	O
used	O
in	O
the	O
declaration	O
of	O
a	O
class	O
,	O
method	O
,	O
or	O
field	O
;	O
public	O
classes	O
,	O
methods	B-Language
,	O
and	O
fields	B-Application
can	O
be	O
accessed	O
by	O
the	O
members	O
of	O
any	O
class	O
.	O
</s>
<s>
This	B-Application
keyword	O
is	O
also	O
used	O
to	O
declare	O
that	O
a	O
method	O
returns	O
a	O
value	O
of	O
the	O
primitive	O
type	O
short	O
.	O
</s>
<s>
Used	O
to	O
declare	O
a	O
field	O
,	O
method	O
,	O
or	O
inner	B-Language
class	I-Language
as	O
a	O
class	O
field	O
.	O
</s>
<s>
Classes	O
maintain	O
one	O
copy	O
of	O
class	O
fields	B-Application
regardless	O
of	O
how	O
many	O
instances	O
exist	O
of	O
that	O
class	O
.	O
</s>
<s>
static	B-General_Concept
also	O
is	O
used	O
to	O
define	O
a	O
method	O
as	O
a	O
class	O
method	O
.	O
</s>
<s>
Class	O
methods	B-Language
are	O
bound	O
to	O
the	O
class	O
instead	O
of	O
to	O
a	O
specific	O
instance	O
,	O
and	O
can	O
only	O
operate	O
on	O
class	O
fields	B-Application
.	O
</s>
<s>
Classes	O
and	O
interfaces	B-Language
declared	O
as	O
static	B-General_Concept
members	O
of	O
another	O
class	O
or	O
interface	B-Language
are	O
actually	O
top-level	O
classes	O
and	O
are	O
not	O
inner	O
classes	O
.	O
</s>
<s>
Inheritance	B-Language
basically	O
used	O
to	O
achieve	O
dynamic	O
binding	O
or	O
run-time	O
polymorphism	O
in	O
java	B-Language
.	O
</s>
<s>
Allows	O
a	O
subclass	O
to	O
access	O
overridden	B-Language
methods	B-Language
and	O
hidden	O
members	O
of	O
its	O
superclass	O
.	O
</s>
<s>
The	O
super	B-Language
keyword	O
is	O
also	O
used	O
to	O
forward	O
a	O
call	O
from	O
a	O
constructor	O
to	O
a	O
constructor	O
in	O
the	O
superclass	O
.	O
</s>
<s>
Used	O
in	O
the	O
declaration	O
of	O
a	O
method	O
or	O
code	O
block	O
to	O
acquire	O
the	O
mutex	B-Operating_System
lock	I-Operating_System
for	B-Language
an	O
object	O
while	O
the	O
current	O
thread	B-Operating_System
executes	O
the	O
code	O
.	O
</s>
<s>
For	B-Language
static	B-Language
methods	I-Language
,	O
the	O
object	O
locked	O
is	O
the	O
class	O
's	O
Class	O
.	O
</s>
<s>
Guarantees	O
that	O
at	O
most	O
one	O
thread	B-Operating_System
at	O
a	O
time	O
operating	O
on	O
the	O
same	O
object	O
executes	O
that	O
code	O
.	O
</s>
<s>
The	O
mutex	B-Operating_System
lock	I-Operating_System
is	O
automatically	O
released	O
when	O
execution	O
exits	O
the	O
synchronized	B-Operating_System
code	O
.	O
</s>
<s>
Fields	B-Application
,	O
classes	O
and	O
interfaces	B-Language
cannot	O
be	O
declared	O
as	O
synchronized	B-Operating_System
.	O
</s>
<s>
this	B-Application
can	O
be	O
used	O
to	O
access	O
class	O
members	O
and	O
as	O
a	O
reference	O
to	O
the	O
current	O
instance	O
.	O
</s>
<s>
The	O
this	B-Application
keyword	O
is	O
also	O
used	O
to	O
forward	O
a	O
call	O
from	O
one	O
constructor	O
in	O
a	O
class	O
to	O
another	O
constructor	O
in	O
the	O
same	O
class	O
.	O
</s>
<s>
This	B-Application
causes	O
execution	O
to	O
continue	O
with	O
the	O
first	O
enclosing	O
exception	O
handler	O
declared	O
by	O
the	O
catch	O
keyword	O
to	O
handle	O
an	O
assignment	O
compatible	O
exception	O
type	O
.	O
</s>
<s>
If	O
no	O
exception	O
handler	O
is	O
found	O
in	O
any	O
method	B-Language
call	I-Language
on	O
the	O
stack	O
,	O
then	O
the	O
exception	O
is	O
passed	O
to	O
the	O
thread	B-Operating_System
's	O
uncaught	O
exception	O
handler	O
.	O
</s>
<s>
Declares	O
that	O
an	O
instance	O
field	O
is	O
not	O
part	O
of	O
the	O
default	O
serialized	B-Application
form	O
of	O
an	O
object	O
.	O
</s>
<s>
When	O
an	O
object	O
is	O
serialized	B-Application
,	O
only	O
the	O
values	O
of	O
its	O
non-transient	O
instance	O
fields	B-Application
are	O
included	O
in	O
the	O
default	O
serial	O
representation	O
.	O
</s>
<s>
When	O
an	O
object	O
is	O
deserialized	O
,	O
transient	B-Device
fields	B-Application
are	O
initialized	O
only	O
to	O
their	O
default	O
value	O
.	O
</s>
<s>
when	O
a	O
serialPersistentFields	O
table	O
is	O
declared	O
in	O
the	O
class	O
hierarchy	O
,	O
all	O
transient	B-Device
keywords	O
are	O
ignored	O
.	O
</s>
<s>
The	O
void	O
keyword	O
is	O
used	O
to	O
declare	O
that	O
a	O
method	O
does	O
not	O
return	B-Language
any	O
value	O
.	O
</s>
<s>
Used	O
in	O
field	O
declarations	O
to	O
guarantee	O
visibility	O
of	O
changes	O
to	O
variables	O
across	O
threads	B-Operating_System
.	O
</s>
<s>
Every	O
read	O
of	O
a	O
volatile	B-Operating_System
variable	I-Operating_System
will	O
be	O
read	O
from	O
main	O
memory	O
,	O
and	O
not	O
from	O
the	O
CPU	O
cache	O
,	O
and	O
that	O
every	O
write	O
to	O
a	O
volatile	B-Operating_System
variable	I-Operating_System
will	O
be	O
written	O
to	O
main	O
memory	O
,	O
and	O
not	O
just	O
to	O
the	O
CPU	O
cache	O
.	O
</s>
<s>
Methods	B-Language
,	O
classes	O
and	O
interfaces	B-Language
thus	O
cannot	O
be	O
declared	O
volatile	B-Operating_System
,	O
nor	O
can	O
local	O
variables	O
or	O
parameters	O
.	O
</s>
<s>
The	O
while	O
keyword	O
is	O
used	O
to	O
create	O
a	O
while	O
loop	O
,	O
which	O
tests	O
a	O
boolean	O
expression	O
and	O
executes	O
the	O
block	O
of	O
statements	O
associated	O
with	O
the	O
loop	O
if	O
the	O
expression	O
evaluates	O
to	O
true	O
;	O
this	B-Application
continues	O
until	O
the	O
expression	O
evaluates	O
to	O
false	O
.	O
</s>
<s>
This	B-Application
keyword	O
can	O
also	O
be	O
used	O
to	O
create	O
a	O
do-while	O
loop	O
;	O
see	O
do	O
.	O
</s>
<s>
Used	O
to	O
declare	O
that	O
a	O
class	O
or	O
interface	B-Language
which	O
extends	B-Language
a	O
sealed	O
class	O
can	O
be	O
extended	O
by	O
unknown	O
classes	O
.	O
</s>
<s>
A	O
sealed	O
class	O
or	O
interface	B-Language
can	O
only	O
be	O
extended	O
or	O
implemented	O
by	O
classes	O
and	O
interfaces	B-Language
permitted	O
to	O
do	O
so	O
.	O
</s>
<s>
A	O
special	O
identifier	O
that	O
cannot	O
be	O
used	O
as	O
a	O
type	O
name	O
(	O
since	O
Java	B-Language
10	O
)	O
.	O
</s>
<s>
Used	O
to	O
set	O
a	O
value	O
for	B-Language
a	O
switch	O
expression	O
,	O
when	O
using	O
labelled	O
statement	O
groups	O
(	O
for	B-Language
example	O
,	O
case	O
L	O
:	O
)	O
.	O
</s>
<s>
Although	O
reserved	O
as	O
a	O
keyword	O
in	O
Java	B-Language
,	O
const	O
is	O
not	O
used	O
and	O
has	O
no	O
function	O
.	O
</s>
<s>
For	B-Language
defining	O
constants	O
in	O
Java	B-Language
,	O
see	O
the	O
final	B-Language
keyword	O
.	O
</s>
<s>
Although	O
reserved	O
as	O
a	O
keyword	O
in	O
Java	B-Language
,	O
goto	B-Application
is	O
not	O
used	O
and	O
has	O
no	O
function	O
.	O
</s>
<s>
Although	O
reserved	O
as	O
a	O
keyword	O
in	O
Java	B-Language
,	O
strictfp	B-Language
is	O
obsolete	O
,	O
and	O
no	O
longer	O
has	O
any	O
function	O
.	O
</s>
<s>
Previously	O
this	B-Application
keyword	O
was	O
used	O
to	O
restrict	O
the	O
precision	O
and	O
rounding	O
of	O
floating	B-Algorithm
point	I-Algorithm
calculations	O
to	O
ensure	O
portability	O
.	O
</s>
