Does the stream.spliterator() implicitly closes the stream, or there is a need to explicitly close it afterwards? At first glance, it seems that the .spliterator() method closes the stream, but without calling stream.close(). At least if I close it straight away after the .spliterator() method is invoked, it seems not affection the spliterator operations. This question can be extended to
Tag: java-8
Switching Keys in a Map of Maps
How would you use Java 8 streams to swap keys in this map of maps? Or at least clean up this mess a little bit… Map<Type1, Map> to Map<Type2, Map<Type1, String&…
Observer is deprecated in Java 9. What should we use instead of it?
Java 9 came out, and Observer has been deprecated. Why is that? Does it mean that we shouldn’t implement observer pattern anymore? It would be good to know what is a better alternative? Answer Why is that? Does it mean that we shouldn’t implement observer pattern anymore? Answering the latter part first – YES, it does mean you shouldn’t implement
Way to parseInt without try-catch in Java 8?
Is there a better way to try to convert to int a string that can be or not an integer? Integer.parseInt(String value) will work well with “25” or “019” but not with “hello” or “8A”. In Java 8, we have optional values, for example: You do not need to check nulls, because the Optional wrapper expose useful methods to deal
Java Stream filter with regex not working
hope somebody can help me. I have a ArrayList of a Invoice class. What I’m trying to get is to filter this ArrayListand find the first element which one of its properties matches with a regex. The Invoiceclass looks like this: I’m filtering with this regex (\D+) in order to find if there is any value in the orderNumproperty that
What is the purpose of a static method in interface from Java 8?
Why are static methods supported from Java 8? What is the difference between the two lines in main method in below code? As we can see above, I is not even implemented in B. What purpose would it serve to have a static method in an interface when we can write the same static method in another class and call
Transform List into Map using only two keys and odd or even list indexes as values – Java 8 Stream
I would like to transform list into map using as key values only two string values. Then as values just list of strings containing elements from odd or even index positions from input list. Here is old fashion code: How to transform this code into Java 8 using streams to get this result? My current messy attempt require modifying elements
try-with-resource – finally keyword error on Java 8 [closed]
Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers. This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers. Closed 5 years ago. Improve this question
What advantage is there to using Spring @Async vs. CompleteableFuture directly?
What’s the advantage of using Spring Async vs. Just returning the CompletableFuture on your own? Answer Your application is managed by the container. Since it’s discouraged to spawn Threads on you own, you can let the container inject a managed Executor.
Prime number in java 8
I was trying to write a simple prime number program in Java 8. Below is the program. I wanted to reduce the code in isPrime() as well. Is there something that filters the elements from 2 to n/2, and then apply filter for n%i == 0 which would make isPrime irrelevant? Answer IntStream can be used to generate integer stream