So, to manage our project dependencies you probably will choose Maven or another Deps Management Tools, in my case I use Maven. But today I walk into a hell hole when one of my project suddenly stopped compiling, to know exactly what was happening here is the context:
<li>Netbeans started reporting that cold not locate some Jars</li>
<li>When building and deploying the Maven process started reporting that could not locate the parents POM</li>
So, the first problem is about downloading the JAR file from the maven public repository, when you have a connection problem the Maven will create a jar blank file and will not try to download a new once. To fix this you will need to delete the folder that`s contains the jar file. To find you'll find a .m2 file inside your user folder. This folder contains all the jars files that Maven have downloaded to you.
Now the second problem is about that your POM file contains a segment <parent> and the root POM doesn't exists, to fix this just remove this section and all will work just fine.
To everyone who want to know what the heck is Maven, there is http://maven.apache.org