44 lines
1.6 KiB
Plaintext
44 lines
1.6 KiB
Plaintext
== Why is this an issue?
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Java 21 introduces the new Sequenced Collections API, which is applicable to all collections with a defined sequence on their elements, such as `LinkedList`, `TreeSet`, and others (see https://openjdk.org/jeps/431[JEP 431]).
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For projects using Java 21 and onwards, this API should be utilized instead of workaround implementations that were necessary before Java 21.
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This rule reports when a collection is iterated in reverse through explicit implementation or workarounds, instead of using the reversed view of the collection.
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== How to fix it
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Replace the reported statement with a forward-iteration over the reversed view of the collection.
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=== Code examples
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==== Noncompliant code example
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[source,java,diff-id=1,diff-type=noncompliant]
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----
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void printLastToFirst(List<String> list) {
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for (var it = list.listIterator(list.size()); it.hasPrevious();) {
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var element = it.previous();
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System.out.println(element);
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}
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}
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----
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==== Compliant solution
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[source,java,diff-id=1,diff-type=compliant]
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----
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void printLastToFirst(List<String> list) {
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for (var element: list.reversed()) {
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System.out.println(element);
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}
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}
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----
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== Resources
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=== Documentation
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* Java Documentation - https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/util/SequencedCollection.html[Interface SequencedCollection]
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* OpenJDK - https://openjdk.org/jeps/431[JEP 431: Sequenced Collections]
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* Java Documentation - https://docs.oracle.com/en/java/javase/21/core/creating-sequenced-collections-sets-and-maps.html#GUID-DCFE1D88-A0F5-47DE-A816-AEDA50B97523[Creating Sequenced Collections, Sets, and Maps]
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