During installation, the Java ES installer surveys the software that is already installed on the host where you are installing and identifies the following:
Compatible Java ES product components are installed.
Compatible components do not need to be reinstalled and will not be available for selection in the installer.
Incompatible Java ES product components are installed.
If the installer identifies incompatibilities between components you have selected and components that are already installed locally, you might be prompted to remove or upgrade the incompatible installed component. The installer cannot continue until these incompatibilities are resolved. After resolution, you can refresh the component selection list, and continue with installation.
Incompatible Java ES shared components are installed.
It is not uncommon for existing hosts to already contain versions of Java ES shared components, such as J2SE or NSS. If the installer finds shared components whose version is incompatible with the version of Java ES you are installing, those shared components are listed. If you proceed with installation, the installer upgrades the shared components to compatible versions.