The original state diagram describes the dynamic behavior of the entity based on event response, and shows how the entity reacts to different events according to its current state. UML state diagrams are usually created for the following research purposes: to study the complex behavior of classes, roles, subsystems or components. Simplify the original state table displayed in the summary table.

Extended data:

State machine is used to model the dynamic behavior of model elements, more specifically, it is the event-driven aspect of system behavior (see concept: events and signals).

State machines are dedicated to defining state-dependent behaviors (that is, behaviors that change according to the state of model elements). Model elements whose behavior does not change with their element states do not need a state machine to describe their behavior (these elements are usually passive classes of main load management data).

A state machine consists of states, which are linked together by transformations. State is the condition when an object performs an activity or waits for an event. A transition is a relationship between two states, which is triggered by an event and then performs a specific operation or evaluation and leads to a specific end state.

A simple editor can be regarded as a finite state machine, whose state is empty, waiting for a command and waiting for text.

Events such as Load file, Insert text, Insert character, and Saveandquit cause state machine transitions. Figure 2 below describes the editor's state machine.