Cloud9 IDE/Java
Cloud9 may be used for Java development, but by default the Java Development Kit (JDK) is not installed. This is indicated by the following error when running a .java file:
bash: line 3: javac: command not found
To install the Java Development Kit on Cloud9, enter the following commands at the bash prompt. If you don't see a bash prompt, open a New Terminal window.
sudo apt-get update
sudo apt-get -y install default-jdk