I want to get index when traverse list use lambda. For example: EDIT: The checkBoxes = null; is just a placeholder but will be used properly once I start writing some code. Answer Here’s how I would do it. Run an IntStream over the indexes of the list. Then filter the indexes based on whether the corres…
Tag: java-8
Spring deserializes a LocalDate in a @RequestBody differently from one in a @RequestParam – why, and can they be the same?
QUESTION: Spring appears to use different deserialization methods for LocalDate depending on whether it appears in a @RequestBody or a request @ReqestParam – is this correct, and if so, is there a way to configure them to be the same throughout an application? BACKGROUND: In my @RestController, I have t…
What is the equivalent way to do Ordering.lexicographical() in Java 8 Comparator?
Is there a way to implement Ordering.lexicographical() with Java 8 Comparator? Comparator.thenCompare seems to be limited in this Answer Seemingly not, no. As a result, Guava still provides this functionality, but in the new class Comparators: https://guava.dev/releases/snapshot/api/docs/com/google/common/col…
extract list inside a list as a single list
I’ve a two POJOs, Sample code below Controller class This returns me a list of the list: but what I want is a single list like How can I do that with Java 8 streams? I’ve tried flatMap also, but that doesn’t go well with the Object datatype of entries. Answer Consider a List<String> as…
When should I use streams?
I just came across a question when using a List and its stream() method. While I know how to use them, I’m not quite sure about when to use them. For example, I have a list, containing various paths to different locations. Now, I’d like to check whether a single, given path contains any of the pat…
“Double” composition with CompletableFuture
I’m trying to avoid nesting CompletableFuture when combining 2 independent ones with a BiFunction that returns a third one. Currently, using thenCombine() does not cut it: I’m basically trying to find a way that looks like haskell if there was a CompletableFuture monad: I read somewhere that join(…
I have an enum, but i dont know how can I use correctly?
I searched so long for what enums are useful. In my Opinion there are Variables with many keywords. So have to programming a program what Is used to manage a bank. My Enum has 2 Variables EINZAHLUNG(Deposit) and AUSZAHLUNG(Payout). So I have an class Menue which is provide to call the Methods. The menue would…
How to set sourceCompatability to javaVersion.VERSION_1_8
I installed jdk1.8.0_112 and write code below in build.gradle i received this error Can anyone help me? Answer from https://developer.android.com/guide/platform/j8-jack.html, you also need following: UPDATE Note that Jack toolchain is now deprecated https://android-developers.googleblog.com/2017/03/future-of-…
Stream Way to get index of first element matching boolean
I have a List<Users>. I want to get the index of the (first) user in the stream with a particular username. I don’t want to actually require the User to be .equals() to some described User, just to have the same username. I can think of ugly ways to do this (iterate and count), but it feels like t…
Initialize list if list is null with lombok getter?
I am currently replacing all my standard POJO’s to use Lombok for all the boilerplate code. I find myself keeping getters for lists because I want to return an empty list if the list has not been initialized. That is, I don’t want the getter to return null. If there some lombok magic that I’…