ArchiCAD 16 Hotfixes
If you are installing an ArchiCAD 16 Hotfix onto a Windows platform Java 6 will be required even if Java version 7 is already installed on your computer. If Java 6 is not present on your Windows you can download and install from here. The two Java Versions will not interfere.
ArchiCAD 16
If you are installing ArchiCAD 16 and Java version 7 is installed on your computer, the installer (or un-installer) of ArchiCAD will install the required Java version 1.6.32. The two Java Versions will not interfere.
ArchiCAD 11 - ArchiCAD 15
If you are installing ArchiCAD 11-15 and Java version 7 is installed, the installers (or un-installers) of ArchiCAD won't work. To make them work:
Temporarily uninstall the v7 Java version
open Control Panel
Add/Remove programs
Remove Java 7