switch Statement UML Activity Diagram

Figure 5.12 shows the UML activity diagram for the general switch multiple-selection statement. Most switch statements use a break in each case to terminate the switch statement after processing the case. Figure 5.12 emphasizes this by including break statements in the activity diagram. Without the break statement, control would not transfer to the first statement after the switch statement after a case is processed. Instead, control would transfer to the next case’s actions.

Fig. 5.12. switch multiple-selection statement UML activity diagram with break statements.

The diagram makes it clear that the break statement at the end of a case causes control to exit the switch statement immediately. Again, note that (besides an initial state, transition arrows, a final state and several notes) the diagram contains action states and decisions. Also, the diagram uses merge symbols to merge the transitions from the break statements to the final state.

Each case can be used to test only an integral constant expression—any combination of character constants and integer constants that evaluates to a constant integer value. A character constant is represented as the specific character in single quotes, such as 'A'. An integer constant is simply an integer value. Also, each case label can specify only one integral constant expression.