Clean list and destroy activities.
Retrieve current activity for layer.
Retrieve current activity for layer.
Throws IllegalArgumentException if layer index is out of allowed layers.
layer index
an activity that currently processed within layer
Whether there is any activity in the list.
Whether there is any activity in the list.
whether there is any activity in the list
Returns total length of the list.
Returns total length of the list.
total length of the list
Retrieve current activity for layer and remove it from list.
Retrieve current activity for layer and remove it from list.
Throws IllegalArgumentException if layer index is out of allowed layers.
layer index
an activity that currently processed within layer
Sets an activity that currently used by user.
Sets an activity that currently used by user.
Throws IllegalArgumentException if layer index is out of allowed layers.
of a currently processed activity
an activity that currently processed
An activity list that used for simplification of the usage activity' array.