You can use it in combination with the Elvis operator. Same as isNullOrEmpty() and will ALSO return true for whitespace. isNullOrBlank() returns true for a string with no characters and/or zero length. Note that if the variable is a mutable property, you won't be able to smart cast it to its non-nullable type inside the if statement (because the value might have been modified by another thread) and you'd have to use the safe call operator with let instead. isNullOrEmpty() returns true for a string with no characters and/or zero length as Wyck commented. Nullable types are followed by the character. Therefore when comparing to null, the structural equality a = null is translated to a referential equality a = null.Īccording to the docs, there is no point in optimizing your code, so you can use a = null and a != null In Kotlin, each type is consider non-null, but each of those types have a derived type nullable.
The method below demonstrates how to use the firstOrNull() method.A structural equality a = b is translated to a?.equals(b) ?: (b = null) If no element matches the given predicate function, then null is returned. This works fine, but is there something like this already available in the language / lib The. This method returns the first element from the list that satisfies the provided the predicate. That is, if x is null, then map it to null, else map it to f(x). This method takes a predicate function as an argument. 20 Likes, 0 Comments - Elewayte (elewayteedu) on Instagram: 'PYTHON: Python is the superhero of programming languages, versatile for web & software developmen. Syntax to get the first element that matches the predicate fun List.firstOrNull( Returns the first element if the ArrayList is not empty. Syntax to get the first element // to get first element If no element matches the provided predicate function, then null is returned. To get the first element of the ArrayList that satisfies the provided predicate function Predicate is a Functional interface, which takes one argument and returns either true or false based on the condition defined.If the ArrayList is empty, then null is returned. To get the first element of the ArrayList.The firstOrNull() method can be used in two ways.
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