In this section, we will be installing a file transfer application, installing Java, and preparing the NetBeans editor.

We will be using the Oracle JDK to run our Java applications. At the time of writing, the latest version is JDK 1.8, which all our projects will be using as a minimal version:

We can now close FileZilla and do the final steps required to install this Java version.

ssh [email protected]

The connection we make is done with ssh, which is a small terminal application that creates a secure connection with the Raspberry Pi. We use pi as the username where the @ character literally means at because we log in as this user at the specified IP address. In the preceding command-line example, I have used the 192.168.1.20 IP address of my Raspberry Pi. You should replace this with the IP address you have set for yours. We are now asked to enter the password; enter the password that has been set for the user pi during the preparation.

From this point on it does not matter how we are logged in on the Raspberry Pi as the following steps are the same via Windows with PuTTY, Mac with terminal, or using the keyboard with a display attached to the Raspberry Pi. We are now presented with the CLI on the Raspberry Pi, which gives us the opportunity to unpack and install the Java package we have uploaded to the Raspberry Pi. We will place this installation in the /opt/ directory. To make this possible we first create the java directory inside the /opt/ directory by entering the following command:

sudo mkdir /opt/java

We use the sudo command because this directory is owned by the root user, which is the administrator on the Raspberry Pi. The sudo command temporarily leverages our privileges to be an administrator for the duration of the command. With mkdir /opt/java we created the java directory inside the /opt/ directory. Now that we have the /opt/java directory we are going to unpack the downloaded Java archive file. We do this by entering the following command:

sudo tar -C /opt/java -xf jdk-8u91-linux-
       arm32-vfp-
       hflt.tar.gz

Again we have used the sudo command to leverage our permissions. With the tar utility we unpack the Java archive into the /opt/java directory with the help of the -C parameter line switch. The command line parameters -xf tells the tar utility that we want to unpack the jdk-8u91-linux-arm32-vfp-hflt.tar.gz file. The filename in the preceding example is the version downloaded at the time of writing. Replace  91 with the version you have downloaded.

We can now check if the files have been extracted correctly from the downloaded Java archive. By entering the following command we should see the directory extracted from the archive:

ls -la /opt/java/

If you see the jdk1.8.0_91 directory, as shown the following screenshot, we have successfully unpacked Java. If you have a different version of the JDK, you will see a different number than 91 at the end: