<s>
Free	B-Language
Java	I-Language
implementations	I-Language
are	O
software	O
projects	O
that	O
implement	O
Oracle	O
's	O
Java	B-Device
technologies	I-Device
and	O
are	O
distributed	O
under	O
free	B-License
software	I-License
licences	I-License
,	O
making	O
them	O
free	B-Application
software	I-Application
.	O
</s>
<s>
Sun	O
released	O
most	O
of	O
its	O
Java	B-Language
source	I-Language
code	I-Language
as	O
free	B-Application
software	I-Application
in	O
May	O
2007	O
,	O
so	O
it	O
can	O
now	O
almost	O
be	O
considered	O
a	O
free	B-Language
Java	I-Language
implementation	I-Language
.	O
</s>
<s>
Java	B-Device
implementations	O
include	O
compilers	O
,	O
runtimes	O
,	O
class	O
libraries	O
,	O
etc	O
.	O
</s>
<s>
Advocates	O
of	O
free	B-License
and	I-License
open	I-License
source	I-License
software	I-License
refer	O
to	O
free	O
or	O
open	O
source	O
Java	B-Language
virtual	I-Language
machine	I-Language
software	O
as	O
free	B-Language
runtimes	I-Language
or	O
free	B-Language
Java	I-Language
runtimes	I-Language
.	O
</s>
<s>
Some	O
advocates	O
in	O
this	O
movement	O
prefer	O
not	O
to	O
use	O
the	O
term	O
"	O
Java	B-Device
"	O
as	O
it	O
has	O
trademark	O
issues	O
associated	O
with	O
it	O
.	O
</s>
<s>
Hence	O
,	O
even	O
though	O
it	O
is	O
a	O
"	O
free	O
Java	B-Device
movement	O
"	O
,	O
the	O
term	O
"	O
free	B-Language
Java	I-Language
runtimes	I-Language
"	O
is	O
avoided	O
by	O
them	O
.	O
</s>
<s>
The	O
first	O
free	O
project	O
to	O
offer	O
substantial	O
parts	O
of	O
Java	B-Device
platform	I-Device
functionality	O
was	O
likely	O
guavac	O
,	O
which	O
began	O
some	O
time	O
before	O
November	O
1995	O
.	O
</s>
<s>
Since	O
then	O
,	O
the	O
free	B-Application
software	I-Application
movement	O
developed	O
other	O
Java	B-Device
compilers	O
,	O
most	O
notably	O
the	O
GNU	B-Language
Compiler	I-Language
for	I-Language
Java	I-Language
.	O
</s>
<s>
Others	O
include	O
the	O
Eclipse	B-Application
Java	I-Application
Compiler	O
(	O
ECJ	O
)	O
,	O
which	O
is	O
maintained	O
by	O
the	B-Application
Eclipse	I-Application
Foundation	I-Application
,	O
and	O
Jikes	B-Application
,	O
which	O
is	O
no	O
longer	O
actively	O
maintained	O
.	O
</s>
<s>
Since	O
the	O
GNU	B-Application
Compiler	I-Application
Collection	I-Application
's	O
4.3	O
release	O
,	O
GCJ	B-Language
(	O
its	O
Java	B-Device
compiler	O
)	O
is	O
using	O
the	O
ECJ	O
parser	B-Language
front-end	O
for	O
parsing	B-Language
Java	B-Device
.	O
</s>
<s>
Examples	O
of	O
free	O
runtime	B-Language
environments	I-Language
include	O
Kaffe	B-Language
,	O
SableVM	B-Language
and	O
gcj	B-Language
.	O
</s>
<s>
GNU	B-Language
Classpath	I-Language
is	O
the	O
main	O
free	B-Application
software	I-Application
class	B-Library
library	I-Library
for	O
Java	B-Device
.	O
</s>
<s>
Most	O
free	B-Language
runtimes	I-Language
use	O
GNU	B-Language
Classpath	I-Language
as	O
their	O
class	B-Library
library	I-Library
.	O
</s>
<s>
In	O
May	O
2005	O
,	O
Apache	B-Application
Harmony	I-Application
was	O
announced	O
,	O
however	O
,	O
the	O
project	O
chose	O
the	O
Apache	B-Application
License	I-Application
,	O
which	O
was	O
at	O
the	O
time	O
incompatible	O
with	O
all	O
existing	O
free	B-Language
Java	I-Language
implementations	I-Language
.	O
</s>
<s>
Another	O
event	O
in	O
May	O
2005	O
was	O
the	O
announcement	O
that	O
OpenOffice.org	B-Application
2.0	I-Application
would	O
depend	O
on	O
Java	B-Device
features	O
which	O
free	B-Application
software	I-Application
implementations	O
could	O
n't	O
provide	O
.	O
</s>
<s>
Following	O
controversy	O
,	O
OpenOffice.org	B-Application
adopted	O
a	O
guideline	O
requiring	O
it	O
to	O
work	O
with	O
free	B-Language
Java	I-Language
implementations	I-Language
.	O
</s>
<s>
Notable	O
applications	O
that	O
already	O
worked	O
with	O
free	B-Language
software	I-Language
Java	I-Language
implementations	I-Language
before	O
November	O
2006	O
include	O
OpenOffice.org	B-Application
and	O
Vuze	B-Application
,	O
both	O
of	O
which	O
work	O
when	O
compiled	O
with	O
GCJ	B-Language
.	O
</s>
<s>
On	O
13	O
November	O
2006	O
,	O
Sun	O
released	O
its	O
compiler	O
,	O
javac	B-General_Concept
,	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
.	O
</s>
<s>
As	O
of	O
September	O
2007	O
,	O
as	O
well	O
as	O
javac	B-General_Concept
,	O
Sun	O
has	O
released	O
the	O
code	O
of	O
HotSpot	B-Language
(	O
the	O
virtual	B-Architecture
machine	I-Architecture
)	O
and	O
almost	O
all	O
the	O
Java	B-Library
Class	I-Library
Library	I-Library
as	O
free	B-Application
software	I-Application
.	O
</s>
<s>
Following	O
their	O
promise	O
to	O
release	O
a	O
fully	O
buildable	O
JDK	B-Language
based	O
almost	O
completely	O
on	O
free	B-License
and	I-License
open	I-License
source	I-License
code	O
in	O
the	O
first	O
half	O
of	O
2007	O
,	O
Sun	O
released	O
the	O
complete	O
source	O
code	O
of	O
the	O
Class	B-Library
library	I-Library
under	O
the	O
GPL	B-License
on	O
May	O
8	O
,	O
2007	O
,	O
except	O
some	O
limited	O
parts	O
that	O
were	O
licensed	O
by	O
Sun	O
from	O
3rd	O
parties	O
who	O
did	O
not	O
want	O
their	O
code	O
to	O
be	O
released	O
under	O
a	O
free	B-License
software	I-License
licence	I-License
.	O
</s>
<s>
Sun	O
has	O
stated	O
that	O
it	O
aims	O
to	O
replace	O
the	O
parts	O
that	O
remain	O
proprietary	B-Application
and	O
closed	B-Application
source	I-Application
with	O
alternative	O
implementations	O
and	O
make	O
the	O
class	B-Library
library	I-Library
completely	O
free	B-License
and	I-License
open	I-License
source	I-License
.	O
</s>
<s>
Since	O
there	O
's	O
some	O
encumbered	B-Application
code	I-Application
in	O
the	O
JDK	B-Language
,	O
Sun	O
will	O
continue	O
to	O
use	O
that	O
code	O
in	O
commercial	O
releases	O
until	O
it	O
's	O
replaced	O
by	O
fully	O
functional	O
free	B-License
and	I-License
open-source	I-License
alternatives	O
.	O
</s>
<s>
As	O
of	O
May	O
2008	O
,	O
the	O
only	O
part	O
of	O
the	O
Class	B-Library
library	I-Library
that	O
remains	O
proprietary	B-Application
(	O
4%	O
as	O
of	O
May	O
2007	O
for	O
OpenJDK	B-Language
7	O
,	O
</s>
<s>
is	O
the	O
SNMP	B-Protocol
implementation	O
.	O
</s>
<s>
Since	O
the	O
first	O
May	O
2007	O
release	O
,	O
Sun	O
Microsystems	O
,	O
with	O
the	O
help	O
of	O
the	O
community	O
,	O
has	O
released	O
as	O
free	B-Application
software	I-Application
(	O
or	O
replaced	O
with	O
free-software	B-Application
alternatives	O
)	O
almost	O
all	O
the	O
encumbered	B-Application
code	I-Application
:	O
</s>
<s>
The	O
closed-source	B-Application
software	I-Application
synthesizer	O
has	O
been	O
replaced	O
by	O
a	O
new	O
synthesizer	O
developed	O
specifically	O
for	O
OpenJDK	B-Language
called	O
Gervill	O
,	O
</s>
<s>
All	O
cryptography	O
classes	O
used	O
in	O
the	O
Class	B-Library
library	I-Library
have	O
been	O
released	O
as	O
free	B-Application
software	I-Application
,	O
</s>
<s>
FreeType	B-Application
has	O
replaced	O
the	O
code	O
that	O
scales	O
and	O
rasterizes	O
fonts	O
.	O
</s>
<s>
LittleCMS	B-Application
has	O
replaced	O
the	O
native	O
color-management	O
system	O
.	O
</s>
<s>
There	O
is	O
a	O
pluggable	O
layer	O
in	O
the	O
JDK	B-Language
,	O
so	O
that	O
the	O
commercial	O
version	O
can	O
use	O
the	O
old	O
color	O
management	O
system	O
and	O
OpenJDK	B-Language
can	O
use	O
LittleCMS	B-Application
.	O
</s>
<s>
The	O
open-sourced	O
Pisces	O
renderer	O
used	O
in	O
the	O
phoneME	B-Language
project	O
has	O
replaced	O
the	O
anti-aliasing	B-Algorithm
graphics	O
rasterizer	O
code	O
.	O
</s>
<s>
The	O
JavaScript	B-Language
plugin	O
has	O
been	O
open-sourced	O
(	O
the	B-Language
JavaScript	I-Language
engine	I-Language
itself	O
was	O
open-sourced	O
from	O
the	O
beginning	O
)	O
.	O
</s>
<s>
Because	O
of	O
these	O
previously	O
encumbered	O
components	O
,	O
it	O
was	O
not	O
possible	O
to	O
build	O
OpenJDK	B-Language
only	O
with	O
free	B-Application
software	I-Application
components	O
.	O
</s>
<s>
In	O
order	O
to	O
be	O
able	O
to	O
do	O
this	O
before	O
the	O
whole	O
class	B-Library
library	I-Library
is	O
made	O
free	O
,	O
and	O
to	O
be	O
able	O
to	O
bundle	O
OpenJDK	B-Language
in	O
Fedora	O
Core	O
and	O
other	O
free	O
Linux	B-Application
distributions	O
,	O
Red	O
Hat	O
has	O
started	O
a	O
project	O
called	O
IcedTea	B-Language
.	O
</s>
<s>
It	O
is	O
basically	O
an	O
OpenJDK/GNU	O
Classpath	O
hybrid	O
that	O
can	O
be	O
used	O
to	O
bootstrap	O
OpenJDK	B-Language
using	O
only	O
free	B-Application
software	I-Application
.	O
</s>
<s>
As	O
of	O
March	O
2008	O
,	O
the	O
Fedora	O
9	O
distribution	O
has	O
been	O
released	O
with	O
OpenJDK	B-Language
6	O
instead	O
of	O
the	O
IcedTea	B-Language
implementation	O
of	O
OpenJDK	B-Language
7	O
.	O
</s>
<s>
Sun	O
has	O
replaced	O
most	O
of	O
the	O
encumbrances	O
for	O
which	O
IcedTea	B-Language
was	O
providing	O
replacements	O
(	O
less	O
than	O
1%	O
of	O
encumbered	B-Application
code	I-Application
remains	O
in	O
the	O
class	B-Library
library	I-Library
,	O
and	O
this	O
code	O
is	O
not	O
necessary	O
to	O
run	O
OpenJDK	B-Language
)	O
.	O
</s>
<s>
OpenJDK	B-Language
6	O
was	O
a	O
stable	O
branch	O
,	O
whereas	O
OpenJDK	B-Language
7	O
was	O
unstable	O
and	O
not	O
expected	O
to	O
ship	O
a	O
stable	O
release	O
until	O
2009	O
.	O
</s>
<s>
Sun	O
has	O
licensed	O
the	O
OpenJDK	B-Language
trademark	O
for	O
use	O
in	O
Fedora	O
.	O
</s>
<s>
In	O
June	O
2008	O
,	O
it	O
was	O
announced	O
that	O
IcedTea	B-Language
6	O
(	O
as	O
the	O
packaged	O
version	O
of	O
OpenJDK	B-Language
on	O
Fedora	O
9	O
)	O
had	O
passed	O
the	O
Technology	B-Language
Compatibility	I-Language
Kit	I-Language
tests	O
and	O
can	O
claim	O
to	O
be	O
a	O
fully	O
compatible	O
Java	B-Device
6	O
implementation	O
.	O
</s>
<s>
In	O
September	O
2013	O
,	O
Azul	O
Systems	O
released	O
Zulu	O
,	O
a	O
free	O
,	O
open	O
source	O
build	O
of	O
OpenJDK	B-Language
for	O
Windows	B-Device
Server	I-Device
and	O
the	O
Microsoft	B-Application
Azure	I-Application
Cloud	O
.	O
</s>
<s>
Later	O
releases	O
added	O
support	O
for	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
multiple	O
versions	O
of	O
Linux	B-Application
and	O
the	O
Java	B-Language
Platform	I-Language
,	I-Language
Standard	I-Language
Edition	I-Language
version	O
8	O
.	O
</s>
<s>
Zulu	O
is	O
certified	O
compliant	O
with	O
Java	B-Language
SE	I-Language
8	O
,	O
7	O
and	O
6	O
using	O
the	O
OpenJDK	B-Language
Community	O
Technology	B-Language
Compatibility	I-Language
Kit	I-Language
.	O
</s>
<s>
Amazon	B-Application
have	O
released	O
Amazon	B-Application
Corretto	O
a	O
no-cost	O
,	O
multiplatform	O
,	O
production-ready	O
distribution	O
of	O
the	O
Open	B-Language
Java	I-Language
Development	I-Language
Kit	I-Language
.	O
</s>
<s>
It	O
is	O
released	O
under	O
GPL	B-License
v2	O
with	O
the	O
Classpath	O
Exception	O
.	O
</s>
<s>
Long	O
term	O
support	O
versions	O
of	O
Java	B-Device
8	O
and	O
Java	B-Device
11	O
are	O
available	O
.	O
</s>
<s>
In	O
2017	O
,	O
the	B-Application
Eclipse	I-Application
Foundation	I-Application
released	O
AdoptOpenJDK	B-Language
,	O
now	O
named	O
Adoptium	B-Language
,	O
who	O
's	O
main	O
goal	O
is	O
"	O
to	O
promote	O
and	O
support	O
free	B-License
and	I-License
open-source	I-License
high-quality	O
runtimes	O
and	O
associated	O
technology	O
for	O
use	O
across	O
the	O
Java	B-Device
ecosystem.	O
"	O
</s>
