16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
98 lines
2.2 KiB
Plaintext
98 lines
2.2 KiB
Plaintext
== Why is this an issue?
|
|
|
|
When using null-related annotations at global scope level, for instance using ``++javax.annotation.ParametersAreNonnullByDefault++`` (from JSR-305) at package level, it means that all the parameters to all the methods included in the package will, or should, be considered Non-``++null++``. It is equivalent to annotating every parameter in every method with non-null annotations (such as ``++@Nonnull++``).
|
|
|
|
|
|
The rule raises an issue every time a parameter could be ``++null++`` for a method invocation, where the method is annotated as forbidding null parameters.
|
|
|
|
|
|
=== Noncompliant code example
|
|
|
|
[source,java]
|
|
----
|
|
@javax.annotation.ParametersAreNonnullByDefault
|
|
class A {
|
|
|
|
void foo() {
|
|
bar(getValue()); // Noncompliant - method 'bar' do not expect 'null' values as parameter
|
|
}
|
|
|
|
void bar(Object o) { // 'o' is by contract expected never to be null
|
|
// ...
|
|
}
|
|
|
|
@javax.annotation.CheckForNull
|
|
abstract Object getValue();
|
|
}
|
|
----
|
|
|
|
|
|
=== Compliant solution
|
|
|
|
Two solutions are possible:
|
|
|
|
* The signature of the method is correct, and null check should be done prior to the call.
|
|
* The signature of the method is not coherent and should be annotated to allow null values being passed as parameter
|
|
|
|
[source,java]
|
|
----
|
|
@javax.annotation.ParametersAreNonnullByDefault
|
|
abstract class A {
|
|
|
|
void foo() {
|
|
Object o = getValue();
|
|
if (o != null) {
|
|
bar(o); // Compliant - 'o' can not be null
|
|
}
|
|
}
|
|
|
|
void bar(Object o) {
|
|
// ...
|
|
}
|
|
|
|
@javax.annotation.CheckForNull
|
|
abstract Object getValue();
|
|
}
|
|
----
|
|
|
|
or
|
|
|
|
|
|
[source,java]
|
|
----
|
|
@javax.annotation.ParametersAreNonnullByDefault
|
|
abstract class A {
|
|
|
|
void foo() {
|
|
bar(getValue());
|
|
}
|
|
|
|
void bar(@javax.annotation.Nullable Object o) { // annotation was missing
|
|
// ...
|
|
}
|
|
|
|
@javax.annotation.CheckForNull
|
|
abstract Object getValue();
|
|
}
|
|
----
|
|
|
|
ifdef::env-github,rspecator-view[]
|
|
|
|
'''
|
|
== Implementation Specification
|
|
(visible only on this page)
|
|
|
|
=== Message
|
|
|
|
Annotate the parameter with @javax.annotation.Nullable in method declaration, or make sure that null can not be passed as argument
|
|
|
|
|
|
=== Highlighting
|
|
|
|
Principal: Nullable parameter expression (with flow leading to null constraint)
|
|
|
|
Secondary: method declaration (what if in other file?)
|
|
|
|
|
|
endif::env-github,rspecator-view[]
|