BlueJ is a great IDE for learning Java. The installer on the BlueJ website works great for any debain or ubuntu based system. The launcher in BlueJ is geared toward Java 7 so if you are running Java 8 you need to make a small change to the launch script in order to get it to work.
If you need help installing Java 8 in lubuntu, check out this excellent guide from webupd8.
After you have Java and BlueJ installed, if you try to launch it from the programs menu, nothing will happen. If you launch it from the terminal, you get a little bit more indication of what is wrong.
A suitable JDK couldn't be located. You may need to edit the /usr/bin/bluej launch script.
Fortunately, this is an easy fix. Open up a terminal and type:
sudo nano /usr/bin/bluej
On the 14th line of that file you will see
for VMNAME in java-7-oracle jdk
Change the 7 to an 8 on this line. So your file should look something like this:
for VMNAME in java-8-oracle jdk-8-oracle
Press Ctr+X to exit and save the file. Now you will be able to launch BlueJ and hack away in Java!
If you made it this far, you should probably follow me on twitter. 🙂 Follow @levlaz