CODEWITHSUNDEEP
javakotlincollectionsjava-stream
testivanivan
testivanivan

Reputation: 1514

How to safely filter elements in collection?

I have data class Product:

data class Product(
    val name: String,
    val code: String?
)

And I need to get product name from product list by given code. Here is my code in Kotlin:

 val productList = getProductList()
    val codeToFind = "1234"

    val nameByCode = productList.firstOrNull { it.code == codeToFind }
        ?.name ?: ""

Is it possible to write the same concise and safe code in the Java using Stream API ?

Upvotes: 0

Views: 85

Answers (1)

star67
star67

Reputation: 1832

Try this:

String nameByCode = getProductList().stream()
           .filter(Objects::nonNull)  // filters null values in the list
           .filter(it -> codeToFind.equals(it.code))
           .findFirst()               // returns java.util.Optional wrapper
           .map(it -> it.getName())   // null-safe operation on the wrapper
           .orElse("");               // fallback value

Links:

https://docs.oracle.com/javase/8/docs/api/java/util/Optional.html https://docs.oracle.com/javase/8/docs/api/java/util/Objects.html#nonNull-java.lang.Object-

Upvotes: 3

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