39 lines
1.1 KiB
Plaintext
39 lines
1.1 KiB
Plaintext
== Why is this an issue?
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Passing a collection as an argument to the collection's own method is either an error - some other argument was intended - or simply nonsensical code.
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Further, because some methods require that the argument remain unmodified during the execution, passing a collection to itself can result in undefined behavior.
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== How to fix it
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=== Code examples
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==== Noncompliant code example
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[source,kotlin,diff-id=1,diff-type=noncompliant]
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----
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val objs = mutableListOf<Any>()
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objs.add("Hello")
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objs.add(objs) // Noncompliant; StackOverflowException if objs.hashCode() called
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objs.addAll(objs) // Noncompliant; behavior undefined
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objs.containsAll(objs) // Noncompliant; always true
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objs.removeAll(objs) // Noncompliant; confusing. Use clear() instead
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objs.retainAll(objs) // Noncompliant; NOOP
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----
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==== Compliant solution
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[source,kotlin,diff-id=1,diff-type=compliant]
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----
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val newList = mutableListOf<Any>()
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val objs = mutableListOf<Any>()
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objs.add("Hello")
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objs.containsAll(newList) // Compliant
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objs.addAll(newList) // Compliant
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objs.removeAll(newList) // Compliant
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objs.retainAll(newList) // Compliant
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----
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