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Android Studio is showing the annotation
`@NonNull`
, how can we represent this in UML?
Similarly, how is there a standard to display annotations?
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The @NonNull annotation is the most important among all the annotations of the null-safety feature. We can use this annotation t0 declare non-null constraint anywhere an object reference is expected: a field, a method parameter or a method's return value. Suppose we have a class named Person:
Lombok @NonNull will generate a null-check for the start of a method or constructor body. Lombok NonNull annotation can be declared on instance fields, methods and constructor arguments. 1. Lombok @NoNull on fields
For the @NonNullFields annotation to kick in, we need to create a file named package-info.java in the root directory of the package and annotate the package with @NonNullFields: Let's declare another property in the Person class, called nickName:
In other words: whether or not null annotations "propagate very far" may depend on the tool you use, and on how rigorously you attend to all the warnings issued by the tool.
If you set the multiplicity of your attribute to [1] it becomes not nullable.
- someAttribute : int [1]
And since 1 is the default multiplicity for attributes you can also leave the multiplicity undefined.
- someAttribute : int
In order to allow for null you have to explicitly set the lowerbound to 0
- someAttribute : int [0..1]
See UML 2.5 specification chapter 9.5.4 (Property.Notation)
<multiplicity-range>is the multiplicity range of the Property. If this term is omitted, it implies a multiplicity of 1 (exactly one). (See MultiplicityElement – sub clause 7.5.)
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A NotNull attribute indicates that the property or association end must be present.
This is equivalent to having a multiplicity of 1 rather than 0..1 or an unspecified multiplicity.
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