You may have to recompile Geant4. G4Java needs a slightly modified and corrected version of Geant4 (see Geant4 Modifications).

Get the code and build

You need to check out clhep and geant in parallel. To download geant and clhep type:

svn co svn://
svn co svn://

now you need the platform specific binary distribution for clhep from

Unpack this in clhep/platform where platform is one of "ppc-MacOSX-g++", "i386-Linux-g++" or "x86-Windows-msvc".

Now compile geant by typing

cd geant/source
make includes
make global
cd ..

You can install the specific version for your platform by typing:

make windows
make windows-install


make linux
make linux-install


make macosx
make macosx-install