<s>
Mac	B-Language
OS	I-Language
Runtime	I-Language
for	I-Language
Java	I-Language
(	O
MRJ	O
,	O
originally	O
Macintosh	O
Runtime	O
for	O
Java	B-Language
)	O
was	O
Apple	O
's	O
proprietary	O
virtual	B-Language
machine	I-Language
for	O
Java-based	B-Language
applications	O
in	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
(	O
i.e.	O
</s>
<s>
versions	O
prior	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
)	O
.	O
</s>
<s>
Both	O
a	O
runtime	O
environment	O
and	O
a	O
software	B-Application
development	I-Application
kit	I-Application
(	O
SDK	O
)	O
are	O
available	O
.	O
</s>
<s>
The	O
runtime	O
environment	O
includes	O
a	O
JIT	O
compiler	O
developed	O
by	O
Symantec	O
,	O
the	O
standard	O
Java	B-Language
class	B-Application
library	I-Application
from	O
Sun	O
,	O
additional	O
classes	O
providing	O
Macintosh-specific	O
functionality	O
,	O
and	O
the	O
Apple	O
Applet	B-Language
Runner	O
(	O
a	O
lightweight	O
application	O
for	O
running	O
Java	B-Language
applets	B-Language
without	O
the	O
overhead	O
of	O
a	O
web	B-Application
browser	I-Application
)	O
.	O
</s>
<s>
A	O
number	O
of	O
web	B-Application
browsers	I-Application
could	O
use	O
MRJ	O
to	O
run	O
Java	B-Language
applets	B-Language
in	O
web	O
pages	O
,	O
including	O
Microsoft	B-Application
Internet	I-Application
Explorer	I-Application
,	O
iCab	B-Operating_System
and	O
HotJava	B-Language
.	O
</s>
<s>
The	O
SDK	O
includes	O
ports	O
of	O
most	O
of	O
the	O
tools	O
from	O
Sun	O
's	O
Java	B-Language
Development	I-Language
Kit	I-Language
(	O
in	O
the	O
form	O
of	O
MPW	B-Operating_System
tools	O
and	O
Macintosh	O
applications	O
)	O
,	O
additional	O
tools	O
for	O
packaging	O
Java	B-Language
applications	O
as	O
double-clickable	O
Macintosh	O
applications	O
,	O
libraries	O
for	O
Macintosh-specific	O
functionality	O
,	O
and	O
documentation	O
for	O
the	O
MRJ-specific	O
classes	O
and	O
tools	O
.	O
</s>
<s>
MRJ	O
v2.2.5	O
was	O
compatible	O
with	O
Sun	O
's	O
Java	B-Language
Development	I-Language
Kit	I-Language
version	O
1.1.8	O
.	O
</s>
<s>
Since	O
the	O
transition	O
to	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Apple	O
has	O
discontinued	O
MRJ	O
and	O
instead	O
maintains	O
and	O
distributes	O
a	O
port	O
of	O
Oracle	B-Application
's	I-Application
HotSpot	B-Language
Java	B-Language
virtual	I-Language
machine	I-Language
.	O
</s>
<s>
As	O
of	O
Java	B-Language
7	O
,	O
Apple	O
has	O
discontinued	O
its	O
own	O
JRE	O
,	O
and	O
Java	B-Language
support	O
on	O
OS	O
X/macOS	O
now	O
comes	O
directly	O
from	O
Oracle	B-Application
.	O
</s>
