I have a normal netbeans project and used jdeb to create a deb package. I was hoping to upload that to launchpad ppa i created, but realized that launchpad requires to build the packages itself, probably to have both the sources and the signature so as to have a bit more security and deterrence towards malicious code.
Ok, fine jdeb is out. But how can i build my project from their sandbox considering it's a normal netbeans ant project, not a buildtools project? Also considering that i depend on some (but not all but that is already solved in my ant file) binary jars libraries? Is it impossible without compiling all libraries used that are not in the repositories?
No, you'll have to make sure there are .deb for all the libraries that you are shipping which are built from source.
You'll have to provide a source package which builds the project using ant. To get some inspiration, have a look at an existing package that already does this, e.g. jalview:
apt-get source jalview.