Visibility applies to attributes or operations, and specifies the extent to which other classes can use a given class's attributes or operations.
Three levels of visibility are possible (last symbols are used in UML classes to indicate different levels of visibility): | |||
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public level | usability extends to other classes | + |
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protected level | usability is open only to classes that inherit from original class | # |
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private level | only the original class can use the attribute or operation | - |
Public and private operations in a HardDisk |