<s>
Greenfoot	B-Language
is	O
an	O
integrated	B-Application
development	I-Application
environment	I-Application
using	O
Java	B-Language
or	O
Stride	O
designed	O
primarily	O
for	O
educational	O
purposes	O
at	O
the	O
high	O
school	O
and	O
undergraduate	O
level	O
.	O
</s>
<s>
It	O
allows	O
easy	O
development	O
of	O
two-dimensional	O
graphical	O
applications	B-Application
,	O
such	O
as	O
simulations	O
and	O
interactive	O
games	O
.	O
</s>
<s>
Greenfoot	B-Language
is	O
being	O
developed	O
and	O
maintained	O
at	O
King	O
's	O
College	O
London	O
,	O
with	O
support	O
from	O
Oracle	B-Application
.	O
</s>
<s>
It	O
is	O
free	B-Application
software	I-Application
,	O
released	O
under	O
the	O
GPL	B-License
license	I-License
.	O
</s>
<s>
Greenfoot	B-Language
is	O
available	O
for	O
Windows	B-Application
,	O
macOS	B-Application
,	O
Linux	B-Application
,	O
Solaris	B-Application
,	O
and	O
any	O
recent	O
JVM	B-Language
.	O
</s>
<s>
The	O
Greenfoot	B-Language
project	O
was	O
initiated	O
by	O
Michael	O
Kölling	O
in	O
2003	O
,	O
and	O
a	O
first	O
prototype	O
was	O
built	O
by	O
Poul	O
Henriksen	O
(	O
master	O
's	O
student	O
)	O
and	O
Michael	O
Kölling	O
(	O
supervisor	O
)	O
in	O
2003/2004	O
.	O
</s>
<s>
From	O
2005	O
development	O
was	O
continued	O
involving	O
the	O
other	O
members	O
of	O
the	O
BlueJ	B-Language
Group	O
.	O
</s>
<s>
Greenfoot	B-Language
is	O
being	O
developed	O
and	O
maintained	O
at	O
King	O
's	O
College	O
London	O
,	O
where	O
the	O
development	O
team	O
moved	O
from	O
the	O
University	O
of	O
Kent	O
.	O
</s>
<s>
The	O
first	O
full	O
release	O
,	O
Greenfoot	B-Language
version	O
1.0	O
,	O
was	O
published	O
on	O
31	O
May	O
2006	O
,	O
with	O
further	O
releases	O
following	O
occasionally	O
thereafter	O
.	O
</s>
<s>
In	O
May	O
2007	O
,	O
the	O
Greenfoot	B-Language
project	O
was	O
awarded	O
the	O
"	O
Duke	O
's	O
Choice	O
Award	O
"	O
in	O
the	O
category	O
"	O
Java	B-Language
Technology	I-Language
in	O
Education	O
"	O
,	O
and	O
in	O
2010	O
it	O
won	O
the	O
"	O
Premier	O
Award	O
for	O
Excellence	O
in	O
Engineering	O
Education	O
Courseware	O
"	O
.	O
</s>
<s>
In	O
March	O
2009	O
,	O
Greenfoot	B-Language
project	O
became	O
free	B-Application
and	I-Application
open	I-Application
source	I-Application
software	I-Application
,	O
and	O
licensed	O
under	O
GPL-2.0-or-later	B-License
with	O
the	O
Classpath	O
exception	O
.	O
</s>
<s>
In	O
August	O
2009	O
,	O
a	O
textbook	O
was	O
published	O
that	O
teaches	O
programming	O
with	O
Greenfoot	B-Language
.	O
</s>
<s>
In	O
2017	O
,	O
Greenfoot	B-Language
was	O
extended	O
to	O
support	O
a	O
second	O
programming	O
language	O
,	O
Stride	O
(	O
in	O
addition	O
to	O
Java	B-Language
)	O
.	O
</s>
<s>
Its	O
most	O
notable	O
difference	O
is	O
the	O
use	O
of	O
a	O
frame-based	B-Application
editor	I-Application
.	O
</s>
<s>
The	O
Greenfoot	B-Language
programming	O
model	O
consists	O
of	O
a	O
World	O
class	O
(	O
represented	O
by	O
a	O
rectangular	O
screen	O
area	O
)	O
and	O
any	O
number	O
of	O
actor	O
objects	O
that	O
are	O
present	O
in	O
the	O
world	O
and	O
can	O
be	O
programmed	O
to	O
act	O
independently	O
.	O
</s>
<s>
The	O
world	O
and	O
actors	O
are	O
represented	O
by	O
Java	B-Language
objects	O
and	O
defined	O
by	O
Java	B-Language
classes	O
.	O
</s>
<s>
Greenfoot	B-Language
offers	O
methods	O
to	O
easily	O
program	O
these	O
actors	O
,	O
including	O
method	O
for	O
movement	O
,	O
rotation	O
,	O
changes	O
of	O
appearance	O
,	O
collision	O
detection	O
,	O
etc	O
.	O
</s>
<s>
Programming	O
in	O
Greenfoot	B-Language
at	O
its	O
most	O
basic	O
consists	O
of	O
subclassing	O
two	O
built-in	O
classes	O
,	O
World	O
and	O
Actor	O
.	O
</s>
<s>
An	O
instance	O
of	O
the	O
world	O
subclass	O
represents	O
the	O
world	O
in	O
which	O
Greenfoot	B-Language
execution	O
will	O
occur	O
.	O
</s>
<s>
Execution	O
in	O
Greenfoot	B-Language
consists	O
of	O
a	O
built-in	O
main	O
loop	O
that	O
repeatedly	O
invokes	O
each	O
actor	O
's	O
act	O
method	O
.	O
</s>
<s>
Implementation	O
is	O
done	O
in	O
standard	O
Java	B-Language
.	O
</s>
<s>
Greenfoot	B-Language
offers	O
API	O
methods	O
for	O
a	O
range	O
of	O
common	O
tasks	O
,	O
such	O
as	O
animation	O
,	O
sound	O
,	O
randomisation	O
,	O
and	O
image	O
manipulation	O
.	O
</s>
<s>
All	O
standard	O
Java	B-Language
libraries	O
can	O
be	O
used	O
as	O
well	O
,	O
and	O
sophisticated	O
functionality	O
can	O
be	O
achieved	O
.	O
</s>
<s>
Greenfoot	B-Language
aims	O
to	O
motivate	O
learners	O
quickly	O
by	O
providing	O
easy	O
access	O
to	O
animated	O
graphics	O
,	O
sound	O
and	O
interaction	O
.	O
</s>
<s>
For	O
users	O
of	O
Greenfoot	B-Language
,	O
a	O
community	O
site	O
called	O
the	O
Greenfoot	B-Language
Gallery	O
provides	O
a	O
platform	O
to	O
publish	O
and	O
discuss	O
their	O
projects	O
.	O
</s>
<s>
Anyone	O
can	O
set	O
up	O
an	O
account	O
on	O
the	O
Greenfoot	B-Language
Gallery	O
and	O
publish	O
their	O
work	O
.	O
</s>
<s>
Version	O
3.0	O
added	O
support	O
for	O
the	O
Stride	O
language	O
,	O
and	O
included	O
a	O
novel	O
frame-based	B-Application
editor	I-Application
.	O
</s>
