What nodes do you use to model a loop?

What nodes do you use to model a loop?

• A. Decision and merge nodes
• B. Fork and join nodes
• C. Lifelines
• D. Activity partitions

Answer: (A)

Loops in activity diagrams are modeled using a decision node to test whether to continue and a merge node to bring the flow back together when looping ends. The decision node checks the loop condition and, if true, sends control into the loop body with the option to return to the decision; if false, control passes through the merge and continues with the rest of the process. The edge guards on the decision define the loop condition, making the cycle clear and well-scoped. Fork and join are for parallel paths, not looping. Lifelines belong to sequence diagrams to show object lifetimes, not loop structure. Activity partitions (swimlanes) organize responsibilities or actors, but don’t create loop behavior by themselves.

Loops in activity diagrams are modeled using a decision node to test whether to continue and a merge node to bring the flow back together when looping ends. The decision node checks the loop condition and, if true, sends control into the loop body with the option to return to the decision; if false, control passes through the merge and continues with the rest of the process. The edge guards on the decision define the loop condition, making the cycle clear and well-scoped.

Fork and join are for parallel paths, not looping. Lifelines belong to sequence diagrams to show object lifetimes, not loop structure. Activity partitions (swimlanes) organize responsibilities or actors, but don’t create loop behavior by themselves.