Java Streams: find if stream contains null

tkachuko :

Most probably a duplicate, however I was not able to find any particular one.

Given

public static void main(String[] args) {
    System.out.println(
            Arrays.asList(null, null, 1)
                    .stream()
                    .filter(obj -> obj == null)
                    .findAny()
                    .isPresent()
    );
}

Expectation

Should at least work (i.e return false because findAny returns Optional).

Actual

NullPointerException is thrown

Question

Is it a bug or a feature?

Thanks for your opinion and explanation.

GAdams :

This behavior is highlighted in the Javadoc for findAny() https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#findAny--

Returns:an Optional describing some element of this stream, or an empty Optional if the stream is empty

Throws:NullPointerException - if the element selected is null

Since you are filtering so the Stream only contains nulls, you are getting a NullPointerException as expected.

Guess you like

Origin http://10.200.1.11:23101/article/api/json?id=443266&siteId=1

Java Streams: find if stream contains null

Java streams: Optional to stream

Java Long Stream contains specific number

Java8-14-stream specialized streams and how to construct streams

Java 8 Streams - Collecting Values that could be null

java stream file input / output streams

Java IO streams Comments (five) - buffered stream

java Streams: collect taking in mind stream is empty

Java Streams: distinct() on a pre-sorted stream?

What is byte stream? What byte streams are there in Java

Detailed explanation of Java streams (Stream, Optional)

Stream (Streams)

Reprinted: Java: byte stream and character stream (input and output streams)

Convert Stream<Stream<T>> to T[][] with Streams/Lambda's in Java

Null safe Collection as Stream in Java 8

Null safe Collection as Stream in Java 8

[Java] IO streams - file character stream --FileReader, FileWriter

java study notes: IO stream (input and output streams)

Java 8 Streams - summing multiple values in a type from a stream

Java Streams: put new element through existing stream

Java8 streams: generic logger method in stream

Java 8 nested streams : return a value in last stream

Extracting Map<K, Multiset<V>> from Stream of Streams in Java 8

Java API Streams collecting stream in Map where value is a TreeSet

Advanced Java - the second part of IO Stream "Diverse Streams"

Java implementation: Find whether a given file contains a specific string

How to find max length in list of string using streams in Java?

java streams: easiest way to find adjacent value match

Java 8 Streams find element and add it to the start of the new List

Using Java 8 Streams, how to find the max for a given element in a HashMap