how to represent a consequence relation in a use case? - uml

I'm making a use case diagram for an android application and i want to represent a "consequence" relation but i don't know what to use exactly.To be more clear, i'm calculating something and depending of the result i'm calculating something else, how to repesent that ?
Thank you

A use case diagram shows an objective not working, for that use an activity or sequence diagram.

Related

Extend use case as base case for the include use case

The above use case diagram is to detect fall
So basically, I was trying to use the 'Alarming', 'send SMS' and 'stop SMS' use case as an extension from the base case 'detection of fall' but they also have include relationship as shown in the diagram. Therefore, I tried to do it as shown in the diagram above
Any comments, please? Is it correct?
If you feel the obligation to indicate if conditions in a use-case diagram, it should probably not be a use-case diagram anymore. Try to represent this as an activity diagram, and simplify your use case to something as simple as “Alert for situations of distress”.

Using base use case as include use case

I am trying to draw a use case diagram for navigation. However, I am not sure if it is correct since the 'call out address' base use case is being used as included use case.
Any comments on the above diagram please?
This is not a use case diagram. Your bubbles contain Actions being part if some Activity carried out by a use case. A use case shows added value an actors gets from the system under considertion. Please start at square one!
I recommend reading Bittner/Spence about use case modelling. The best read you can get on that topic.

More than one use case in a single sequence diagram

I want to create a very basic sequence diagram for the first iteration of my app. I have a database of exercises, and I have a use case for creating, another for editing, and another for deleting an exercise. They are all very simple, and use the same elements and actors, like User, DAO, and Database. What I want to do is to create a single SD, that begins with the user asking to create an exercise, followed by the user asking to edit that exercise, and then asking to delete it. My question is: is this considered correct in a sequence diagram? I don't want to create 3 SDs almost identical to one another, and this seems like a simple way to represent all the information, but I don't know if this is correct by UML standards. Thanks.
From a standards conformance point of view, there is nothing in the UML standard, that imposes a relationship between your use case models and sequence diagramme models. So, no matter how many use cases you want to reflect in a sequence diagramme, it would be neither "correct" nor "incorrect".
From a personal point of view : What you are asking about is a question of modeling style, not conformity. As long as the people who are reading your models understand them, you can do whatever you want. So, something like this would be perfectly fine :

Do I have this Use Case diagram correct?

With this Use Case diagram, I'm unsure if I'm currently doing it correctly or not. Checked online and each site is giving me a different answer. I just need a direction or someone to correct me.
This is interesting as I am currently going through the exact same discussion with a client...
I would say "no" simply because I am unsure of what this actually represents.
A use case must bring a benefit to a user, and I really don't this in this diagram. What does Actor0 actually trying to accomplish? I do not get this from the diagram.
Did you write down statements before trying to do this? I find that going to a whiteboard and writing down what your actor's goal and how you see this happening so that the actor achieves the goal is a good start to better understanding the use case and differentiate the system being built from external systems. One way to do this is through a set of user stories (or use case slices).
And answering Thomas Kilian's excellent questions will also help you in this task!
Also, you are doing something that I see too often from people starting with use cases (and sometimes with UML experience): use case decomposition as a set of actions - basically trying to model a set of activities by breaking it down. Doing that is typically the second step in your analysis (e.g., by using activity and sequence diagrams).
No. Only "Register" (what?) and "Add/View Details" (which?) can be regarded as use cases since they add value. Neither "Login" nor "Main Menu" are use cases. The first is a constraint and the second an implementation detail.

use case diagram - conditions or decision node

guys how can I make conditions in use case diagram ? Something like decision node in activity diagram.
For example, If there is "evaluate" usecase which can lead either to Y or N, there is simply no way to express it. There is only constrain feature, that would lead to repeating { if evaluated } {if evaluated } ......
What you probably want to use is alternative paths, basically what you do is you repeat part of your use case like this:
In step 5, if there is not enough money on the account
5.a Show a message to the user
5.b User press "Try a lesser amount" button
5.c System goes to step 3
The Use Case Diagram doesn't seem to fit at all with conditions. Usually, when depicting multiple scenarios, one would make multiple use cases for each one. An activity diagram would be more fitting to display conditional logic.
Usually, conditions (IF) exist somewhere in the use case's activity that would cause the extended use case to occurs. You can add to extended use case to represent yes/no scenarios.

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