Summary

Sub-classes of an active class must be active.

Details

An active class can be seen as a process or a thread. Therefore, if a class is active, all its sub-classes should also be active, since they inherit the process/thread aspect from it.

Tips

If you have non-active sub-classes of an active class:

  • Either make the class non-active

  • Or propagate the active property to all sub-classes.