How to install java JDK on raspberry pi

Question

I am an experienced Java programmer who received the raspberry pi for Christmas. Unfortunately, it appears that only Python is installed in it. What command do I type at the start command line where I would usually type startx to install the JDK and Jre

Answer 1

The oracle 8 preview works for me, thus far. Compiling is slow on the pi, surprise, but the jre seems to run quite fast once it loads. I think bearbin's answer is pretty definitive but if you want a simple way to try oracle:

1. Download. You get a .tar.gz file, which is a gzipped tarball.
2. Put the .tar.gz in /usr/local and unpack it: tar -xzf oracle8-blah-blah.tar.gz. This will create a directory with everything in it. You can rename the directory, mv oracle-jdk-whatever jdk1.8.0. Everything in there is self-contained.
3. Put the bin/ directory at the beginning of your executable search $PATH. If there are any other javas installed, that will make this one take precedence: PATH=/usr/local/jdk1.8.0/bin:$PATH.

That will only work for your current shell. To make it the default from now on, add this to ~/.profile:

export PATH=/usr/local/jdk1.8.0/bin:$PATH

Answer 2

To install the Java Runtime Environment (JRE) run the following command:

sudo apt-get install openjdk-7-jre

This installs the Java JRE (Java Runtime Environment) which will allow you to run applications written in Java.

To install the JDK run the command:

sudo apt-get install openjdk-7-jdk

This allows you to compile Java applications to bytecode.

If you want the Oracle Java VM, which is a lot faster (optimized for embedded arm CPUs) and is also a developer preview (applications maybe buggy or crash) until some time into the future. Instead of the above instructions you need to download the file called Oracle JDK 8 (with JavaFX) for ARM Early Access on the Oracle Java 8 download page.

Remember to download the Oracle Java system on your Pi, or you won't be able to install it.

To install the Oracle Java System:

tar zxvf jdk-8-ea-b36e-linux-arm-hflt-*.tar.gz -C /opt
sudo update-alternatives --install "/usr/bin/java" "java" "/opt/jdk1.8.0/bin/java" 1 
sudo update-alternatives for other commands if needed.
java -version

Then it is all installed.

Another thing, if you have more then one Java runtime installed you have to check which version you use with the commando java -version. If the output is:

java version 1.5.0 gij (GNU libgij)

Then you are using a other java runtime. You can resolve the issue by running

sudo update-alternatives --config java

and choosing the OpenJDK or Oracle option.

Answer 3

sudo apt-get install java-runtime

This is OpenJDK 6.

Oracle JDK is not available in armhf flavor, so you have to use a soft-float image to use it.