Regarding 0 to 1 and 1 to 0 associations in UML

Question

Just want to know how can we differentiate the multiplicities 0..* and 1..*.

For example:

 ---------             ---------
|         |0..*   0..*|         |
|CLASS    |-----------| STUDENT |
|         |           |         |
 ---------             ---------

For this, if we put 1..* in class object, I can see that both represent the same behaviour. Is that right?

0..* ---> Zero or more classes can have zero or more students, which means a class or more classes can have more students or no students. (excluded no class behaviour)

1..* ---> One or more classes can have zero or more students, which means a class or more classes can have more students or no students.

Please correct my understanding?

Nimesh

Answer 1

You have to read it the other way around.

If you have 1..* on the Class end that means that a Student has at least 1 and possible more Classes.

0..* on the Class end means that a student could also have no Classes at all.

Turbo

Thank you... Clearly understand the difference now. – Nimesh