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.infoworld.com/article/2074292/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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