65 lines
1.6 KiB
Plaintext
65 lines
1.6 KiB
Plaintext
== Why is this an issue?
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It's a common pattern to test the result of a ``++java.util.Map.get()++`` against ``++null++`` or calling ``++java.util.Map.containsKey()++`` before proceeding with adding or changing the value in the map. However the ``++java.util.Map++`` API offers a significantly better alternative in the form of the ``++computeIfPresent()++`` and ``++computeIfAbsent()++`` methods. Using these instead leads to cleaner and more readable code.
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*Note* that this rule is automatically disabled when the project's ``++sonar.java.source++`` is not 8.
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=== Noncompliant code example
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[source,java]
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----
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V value = map.get(key);
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if (value == null) { // Noncompliant
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value = V.createFor(key);
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if (value != null) {
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map.put(key, value);
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}
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}
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if (!map.containsKey(key)) { // Noncompliant
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value = V.createFor(key);
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if (value != null) {
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map.put(key, value);
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}
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}
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return value;
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----
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=== Compliant solution
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[source,java]
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----
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return map.computeIfAbsent(key, k -> V.createFor(k));
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----
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=== Exceptions
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This rule will not raise an issue when trying to add ``++null++`` to a map, because ``++computeIfAbsent++`` will not add the entry if the value returned by the function is ``++null++``.
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== Resources
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=== Related rules
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* S6104 - Map "computeIfAbsent()" and "computeIfPresent()" should not be used to add "null" values.
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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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