50 lines
1.6 KiB
Plaintext
50 lines
1.6 KiB
Plaintext
Map https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#computeIfAbsent-K-java.util.function.Function-[computeIfAbsent] and https://docs.oracle.com/javase/8/docs/api/java/util/Map.html#computeIfPresent-K-java.util.function.BiFunction-[computeIfPresent] methods are convenient to avoid the cumbersome process to check if a key exists or not, followed by the addition of the entry. However, when the function used to compute the value returns ``++null++``, the entry ``++key->null++`` will not be added to the Map. Furthermore, in the case of ``++computeIfPresent++``, if the key is present the entry will be removed. These methods should therefore not be used to conditionally add an entry with a null value. The traditional way should be used instead.
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This rule raises an issue when ``++computeIfAbsent++`` or ``++computeIfPresent++`` is used with a lambda always returning null.
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== Noncompliant Code Example
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[source,java]
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----
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map.computeIfAbsent(key, k -> null); // Noncompliant, the map will not contain an entry key->null.
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map.computeIfPresent(key, (k, oldValue) -> null); // Noncompliant
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----
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== Compliant Solution
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[source,java]
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----
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if (!map.containsKey(key)) {
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map.put(key, null);
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}
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if (map.containsKey(key)) {
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map.put(key, null);
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}
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----
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== See Also
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* S3824 - "Map.get" and value test should be replaced with a single method call
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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include::message.adoc[]
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include::highlighting.adoc[]
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'''
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== Comments And Links
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(visible only on this page)
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include::comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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