Use isEmpty() Instead of size(); toList() #2474
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Sonar: Collection.isEmpty() should be used to test for emptiness (java:S1155) CODE_SMELL_MINOR Using Collection.size() to test for emptiness works, but using Collection.isEmpty() makes the code more readable and can be more performant. The time complexity of any isEmpty() method implementation should be O(1) whereas some implementations of size() can be O(n). Also "Stream.toList()" method should be used instead of "collectors" when unmodifiable list needed (java:S6204) CODE_SMELL_MAJOR In Java 8 Streams were introduced to support chaining of operations over collections in a functional style. The most common way to save a result of such chains is to save them to some collection (usually List). To do so there is a terminal method collect that can be used with a library of Collectors. The key problem is that `.collect(Collectors.toList())` actually returns a mutable kind of List while in the majority of cases unmodifiable lists are preferred. In Java 10 a new collector appeared to return an unmodifiable list: `toUnmodifiableList()`. This does the trick but results in verbose code. Since Java 16 there is now a better variant to produce an unmodifiable list directly from a stream: Stream.toList().
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Sonar:
Collection.isEmpty() should be used to test for emptiness (java:S1155)
CODE_SMELL_MINOR
Using Collection.size() to test for emptiness works, but using Collection.isEmpty() makes the code more readable and can be more performant. The time complexity of any isEmpty() method implementation should be O(1) whereas some implementations of size() can be O(n).
Also
"Stream.toList()" method should be used instead of "collectors" when unmodifiable list needed (java:S6204)
CODE_SMELL_MAJOR
In Java 8 Streams were introduced to support chaining of operations over collections in a functional style. The most common way to save a result of such chains is to save
them to some collection (usually List). To do so there is a terminal method collect
that can be used with a library of Collectors. The key problem is that
.collect(Collectors.toList())actually returns a mutable kind of List while in the majority of cases unmodifiable lists are preferred. In Java 10 a new collector appeared to return an unmodifiable list:toUnmodifiableList(). This does the trick but results in verbose code.Since Java 16 there is now a better variant to produce an unmodifiable list
directly from a stream: Stream.toList().