Free but Shackled - The Java Trap
by Richard Stallman
Since this article was first published, Sun
most of its Java platform reference implementation under the GNU
General Public License, and there is now a free development
environment for Java. Thus, the Java language as such is no longer a
You must be careful, however, because not every Java platform is
free. Sun continues distributing an executable Java platform which is
nonfree, and other companies do so too.
The free environment for Java is called IcedTea; the source code
Sun freed is included in that. So that is the one you should use.
Many GNU/Linux distributions come with IcedTea, but some include
nonfree Java platforms.
To reliably ensure your Java programs run fine in a free
environment, you need to develop them using IcedTea. Theoretically
the Java platforms should be compatible, but they are not compatible
In addition, there are nonfree programs with “Java” in
their name, such as JavaFX, and there are nonfree Java packages you
might find tempting but need to reject. So check the licenses of
whatever packages you plan to use. If you use Swing, make sure to use
the free version, which comes with IcedTea.
Aside from those Java specifics, the general issue described here
remains important, because any nonfree library or programming platform
can cause a similar problem. We must learn a lesson from the history of
Java, so we can avoid other traps in the future.
Please also see:
April 12, 2004
If your program is free software, it is basically ethical—but
there is a trap you must be on guard for. Your program, though in
itself free, may be restricted by nonfree software that it depends
on. Since the problem is most prominent today for Java programs, we
call it the Java Trap.
A program is free software if its users have certain crucial
freedoms. Roughly speaking, they are: the freedom to run the
program, the freedom to study and change the source, the freedom to
redistribute the source and binaries, and the freedom to publish
improved versions. (See
Whether any given program in source form is free software depends
solely on the meaning of its license.
Whether the program can be used in the Free World, used by people who mean to
live in freedom, is a more complex question. This is not determined by the
program's own license alone, because no program works in isolation. Every program
depends on other programs. For instance, a program needs to be compiled or
interpreted, so it depends on a compiler or interpreter. If compiled into
byte code, it depends on a byte-code interpreter. Moreover, it needs
libraries in order to run, and it may also invoke other separate programs
that run in other processes. All of these programs are dependencies.
Dependencies may be necessary for the program to run at all, or they may
be necessary only for certain features. Either way, all or part of the
program cannot operate without the dependencies.
If some of a program's dependencies are nonfree, this means that
all or part of the program is unable to run in an entirely free
system—it is unusable in the Free World. Sure, we could
redistribute the program and have copies on our machines, but that's
not much good if it won't run. That program is free software, but it
is effectively shackled by its nonfree dependencies.
This problem can occur in any kind of software, in any language. For
instance, a free program that only runs on Microsoft Windows is clearly
useless in the Free World. But software that runs on GNU/Linux can also be
useless if it depends on other nonfree software. In the past, Motif (before
we had LessTif) and Qt (before its developers made it free software) were
major causes of this problem. Most 3D video cards work fully only with
nonfree drivers, which also cause this problem. But the major source of
this problem today is Java, because people who write free software often
feel Java is sexy. Blinded by their attraction to the language, they
overlook the issue of dependencies and fall into the Java Trap.
Sun's implementation of Java is nonfree. The standard Java libraries are
nonfree also. We do have free implementations of Java, such as the GNU Compiler for Java (GCJ) and GNU Classpath, but they don't support all the
features yet. We are still catching up.
If you develop a Java program on Sun's Java platform, you are liable
to use Sun-only features without even noticing. By the time you find
this out, you may have been using them for months, and redoing the
work could take more months. You might say, “It's too much
work to start over.” Then your program will have fallen into
the Java Trap; it will be unusable in the Free World.
The reliable way to avoid the Java Trap is to have only a free implementation
of Java on your system. Then if you use a Java feature or library that free
software does not yet support, you will find out straightaway, and you can
rewrite that code immediately.
Sun continues to develop additional “standard” Java
libraries, and nearly all of them are nonfree; in many cases, even
a library's specification is a trade secret, and Sun's latest
license for these specifications prohibits release of anything less
than a full implementation of the specification. (See
Fortunately, that specification license does permit releasing an
implementation as free software; others who receive the library can be
allowed to change it and are not required to adhere to the specification.
But the requirement has the effect of prohibiting the use of a collaborative
development model to produce the free implementation. Use of that model would
entail publishing incomplete versions, something those who have read the
spec are not allowed to do.
In the early days of the free software movement, it was impossible to avoid
depending on nonfree programs. Before we had the GNU C compiler, every C
program (free or not) depended on a nonfree C compiler. Before we had the
GNU C library, every program depended on a nonfree C library. Before we had
Linux, the first free kernel, every program depended on a nonfree kernel.
Before we had BASH, every shell script had to be interpreted by a nonfree
shell. It was inevitable that our first programs would initially be hampered
by these dependencies, but we accepted this because our plan included rescuing
them subsequently. Our overall goal, a self-hosting GNU operating system,
included free replacements for all those dependencies; if we reached the goal,
all our programs would be rescued. Thus it happened: with the GNU/Linux system,
we can now run these programs on free platforms.
The situation is different today. We now have powerful free operating systems
and many free programming tools. Whatever job you want to do, you can do it on
a free platform; there is no need to accept a nonfree dependency even
temporarily. The main reason people fall into the trap today is because they
are not thinking about it. The easiest solution to the problem
is to teach people to recognize it and not fall into it.
To keep your Java code safe from the Java Trap, install a free Java
development environment and use it. More generally, whatever
language you use, keep your eyes open, and check the free status of
programs your code depends on. The easiest way to verify that a
program is free is by looking for it in the Free Software Directory
If a program is not in the directory, you can check its license(s)
against the list of free software licenses
We are trying to rescue the trapped Java programs, so if you like the Java
language, we invite you to help in developing GNU Classpath. Trying your
programs with the GCJ Compiler and GNU Classpath, and reporting any
problems you encounter in classes already implemented, is also useful.
However, finishing GNU Classpath will take time; if more nonfree libraries
continue to be added, we may never have all the latest ones. So please don't
put your free software in shackles. When you write an application program
today, write it to run on free facilities from the start.
The Curious Incident
of Sun in the Night-Time