9 ).
152 CHAPTER 3 UML??”Unifi ed Modeling Language
We can assign an initial value to an attribute right away as we defi ne it. Each
new object of the pertaining class will then initially have these values.
We can use property strings predefi ned in UML to specify an attribute more
closely. For example, {ordered} specifi es that a set-type attribute (multiplicity 1) is
ordered, or {nonunique} specifi es that the set of attribute values may contain identical
elements. 4
Several property strings are separated by commas within curly brackets.
The visibility of an attribute is denoted before the name. It states whether or
not the attribute is visible for elements outside the class, which means that it can
be read and written. UML defi nes four different visibility types:
1. public (denoted as )??”the attribute is publicly visible. Each element outside
the class can access this attribute.
2. private (denoted as )??”the attribute is private. No element outside the
class can see this attribute.
3. package (denoted as )??”the attribute is visible to all elements located in
the same package as the class.
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