CPSC 210
C5: Extracting Sequence Diagrams
Learning Goals
- Extract a sequence diagram from a given Java code base
Sequence Diagrams
- Depicts the calls between objects while the system is running
- Vertical timeline of calls from top to bottom
- Starts with a particular method call
A a = new A();
B b = new B();
a.doA(b);
public class A {
public void doA(B b) {
b.doB();
}
}
public class B {
public void doB() { }
}
ObjectsMethod CallsExecution TimelineLifelinesAn Object Calling Its Own Methods
A a = new A();
B b = new B();
a.doA(b);
public class A {
public void doA(B b) {
b.doB();
}
public class B {
public void doB() {
this.doB2();
}
public void doB2() { }
}
Call to same objectParts of the Diagram (again)
Method's execution timeline
Lifelines
Method Calls
Objects alive throughout the execution
Loops & Conditionals
public class RegistrationSystem {
private List<Student> students;
public void printRecords() {
for (Student s : students) {
print(s.getRec());
}
}
}
Our collection
Loop condition
Loop box
Same for conditionals!
if: ...
else if: ...
else: ...
Real
Example
Note: it's a means of communication! It's not all set in stone!
Lecture Ticket Review
Lecture Lab
Lecture Lab
Recommended procedure:
- Sketch your objects and lifelines
- How many lifelines do we need?
- Sketch your loop/alternation boxes
- How many loop/alternation boxes do we need?