PA116 DUM
Statechart diagram
Statechart diagram
aka State diagram or State machine diagram
1) Shows behavior of classes in response to stimuli
2) Used to describe systems with significantly dynamic behavior, i.e.
those that change their states in non-trivial manner
3) The stimuli can be either external or internal
Statechart diagram II
• Illustrates system lifecycle from initation to termination
• Highlights events that cause change of system state
• Records action that are successors to changed states
Notation
State Simple / Composite / Substate
Described by the event that triggered the change from one
state to another
Transition
Initial state
Final state
Fork
Decision
Join
How to model it
1. Decide which parts of system show interesting dynamics of
behavior
2. Identify important objects to be analyzed (see: Class diagram)
3. Identify the states
4. Identify the events that trigger state transition (see: Yourdon‘s
event partitioning, processes in DFD)
5. Repeat steps 3 and 4
Example