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.
70 lines
1.7 KiB
Plaintext
70 lines
1.7 KiB
Plaintext
== Why is this an issue?
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Testing equality of an enum value with ``++equals++`` is perfectly valid because an enum is an Object and every Java developer knows "==" should not be used to compare the content of an Object. At the same time, using "==" on enums:
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* provides the same expected comparison (content) as ``++equals++``
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* is more null-safe than equals()
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* provides compile-time (static) checking rather than runtime checking
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For these reasons, use of "==" should be preferred to ``++equals++``.
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=== Noncompliant code example
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[source,java]
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----
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public enum Fruit {
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APPLE, BANANA, GRAPE
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}
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public enum Cake {
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LEMON_TART, CHEESE_CAKE
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}
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public boolean isFruitGrape(Fruit candidateFruit) {
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return candidateFruit.equals(Fruit.GRAPE); // Noncompliant; this will raise an NPE if candidateFruit is NULL
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}
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public boolean isFruitGrape(Cake candidateFruit) {
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return candidateFruit.equals(Fruit.GRAPE); // Noncompliant; always returns false
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}
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----
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=== Compliant solution
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[source,java]
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----
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public boolean isFruitGrape(Fruit candidateFruit) {
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return candidateFruit == Fruit.GRAPE; // Compliant; there is only one instance of Fruit.GRAPE - if candidateFruit is a GRAPE it will have the same reference as Fruit.GRAPE
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}
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public boolean isFruitGrape(Cake candidateFruit) {
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return candidateFruit == Fruit.GRAPE; // Compliant; compilation time failure
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}
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----
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== Resources
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* https://www.javaworld.com/article/2074292/core-java/use-----or-----to-compare-java-enums.html[Use ++==++ (or !=) to Compare Java Enums]
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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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=== Message
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Use "==" to perform this enum comparison instead of using "equals"
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=== Highlighting
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equals()
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endif::env-github,rspecator-view[]
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