Looking for way to trigger method from outside the class or property condition

I have a class structure that looks like...

classdef Main < handle
    properties
        ObjArray % cell array 1..n with instances of 'System'
    end
    methods
       % Constructor: object array all of the same class 'System' passed in
        function obj = Main(ObjArraySystems)    
            obj.ObjArray = ObjArraySystems; 
        end
        
        % for updating state: some (in this case) some random value passed to each object by a loop
        function update(obj)                    
            for system_id = 1:length(obj.ObjArray)
                value = randi(100);
                obj.ObjArray{system_id}.setState(system_id,value);
            end
        end
    end
end

% System class
classdef System < handle
    properties (Constant)
        State = SystemState
    end
    
    methods
        function setState(obj,system_id,value)
            obj.State.lokalStates(system_id) = value; 
        end
    end
end

% SystemState
classdef SystemState < handle
    properties
        lokalStates  % array holds state for each system, length is number of systems
    end
    
    methods
        function calculationOnArray(obj)
            % performs some calculation on lokalStates array, simple e.g,
            obj.lokalStates = arrayfun(@(x) mean(obj.lokalStates),obj.lokalStates);
        end
    end
end

The desired behavior of the updating process should be as follows: Main passes a new value to each system, these in turn saves the value into a common array (Static Data Object). As soon as the array is 'filled' (last value is passed in), the function ->calculationOnArray should start.

Now, I struggle to find a good solution to trigger the calculation...

1) After the updating loop

obj.ObjArray{1,1}.State.calculationOnArray()

2) calculationOnArray as static method

SystemState.calculationOnArray(obj.ObjArray{1,1}.State)    

3) Some other setmethod inside SystemState

function setState(obj,sytem_id,value) %<- called from 'System'
    obj.lokalStates(system_id) = value; 
    if system_id == obj.NumberofSystems % new property set in constructor of 'SystemState'
        obj.calculationOnArray()
    end
end

4) Best would be if it triggers independently somehow, or the function has a dirct handle to the Main calss...

THX