Kotlin-检查数组包含值的惯用方法

在 Kotlin，检查字符串数组是否包含值的惯用方法是什么。

我想:

array.filter { it == "value" }.any()

还有更好的办法吗？

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最佳答案

The equivalent you are looking for is the contains operator.

array.contains("value")

Kotlin offer an alternative infix notation for this operator:

"value" in array

It's the same function called behind the scene, but since infix notation isn't found in Java we could say that in is the most idiomatic way.

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Using in operator is an idiomatic way to do that.

val contains = "a" in arrayOf("a", "b", "c")

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You can use the in operator which, in this case, calls contains:

"value" in array

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You could also check if the array contains an object with some specific field to compare with using any()

listOfObjects.any{ object -> object.fieldxyz == value_to_compare_here }

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Here is code where you can find specific field in ArrayList with objects. The answer of Amar Jain helped me:

listOfObjects.any{ it.field == "value"}

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You can use it..contains(" ")

 data class Animal (val name:String)




val animals = listOf(Animal("Lion"), Animal("Elephant"), Animal("Tiger"))


println(animals.filter { it.name.contains("n") }.toString())

output will be

[Animal(name=Lion), Animal(name=Elephant)]

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You can use find method, that returns the first element matching the given [predicate], or null if no such element was found. Try this code to find value in array of objects

 val findedElement = array?.find {
it.id == value.id
}
if (findedElement != null) {
//your code here
}