java-8

问题 This question already has answers here : How to use if-else logic in Java 8 stream forEach (4 answers) Closed last year . Scenario: There is a situation where I need to set some values to List of objects based on some field condition using the Java 8 streams API. Below is the sample of object User . public class User{ private int id; private String name; private String text; private boolean isActive; } Here is the code I have worked out List<User> users = userDao.getAllByCompanyId(companyId);

问题 This question already has answers here : How to apply multiple predicates to a java.util.Stream? (4 answers) Closed 3 years ago . I would like to filter out my collection using multiple filters. Let's assume I have a list of Strings and a function filter() to filter out empty Strings. List<String> myList = ....... Typically, I would use streams like this: myList.stream() .filter(elem -> filterOut(elem)) .collect(Collectors.toList()); How to apply multiple filters from a collection ( List or

问题 I am totally new to RxJava and reactive programming. I have an assignment where i must read file and store it to Observable. I have tried to make a Callable with BufferedReader inside and use Observable.fromCallable(), but it didn't work much. Could you please show me how can i do that? I am using RxJava 2.0. 回答1: A basic solution where I use a nested class FileObservableSource to produce the data and then defer the creation of the Observable until an Observer subscribes: import io.reactivex

问题 Is there a way to write a JavaFX app with just JavaScript files now that Nashorn is available in Java 8? Where can I find more info or videos on this? How would you compile it? Or is there a minimal set of bootstrapping files required? 回答1: Yes, you can develop JavaFX programs with just JavaScript (Nashorn). How to access JavaFX from JavaScript Use the jjs -fx yourscript.js command line switch. The -fx flag on jjs will bootstrap scripts using a javafx.application.Application. There is no

问题 Assume I have an infinite Stream. IntStream istream = IntStream.iterate(0, i -> i + 1).limit(100); Stream<Integer> boxedStream = istream.boxed(); Does the boxed() method preserve order? Probably yes, but I cannot find it in the documentation. 回答1: Actually every intermediate operation preserves an order by default. The only exceptions are: unordered() which removes the ordering constraint. sorted() which changes the order. When it's not explicitly specified, you can assume that operation

问题 I have a play 2.4 hibernate postgresql application which works well locally, creates a table automatically initially. But when deployed on heroku it does not create any table though the app loaded without any errors(connected my heroku db from pgAdmin). My Configuration build.sbt name := "lms" version := "1.0" lazy val `lms` = (project in file(".")).enablePlugins(PlayJava) scalaVersion := "2.11.7" libraryDependencies ++= Seq(javaJdbc, cache, javaWs, javaJpa.exclude("org.hibernate.javax

问题 How to count the number of trailing zeroes in an integer using Java 8 Stream/Lambda? Basically the logic should be: keep the integer dividing by 10 as long as the remainder is 0 (the quotient will be supplied to the next division) and count the occurrence(s). e.g. 12300 % 10 == 0 true 1230 % 10 == 0 true 123 % 10 == 0 false Answer: 2 Note: I prefer not to involve String here :-) 回答1: If this is a purely hypothetical question, here is a purely hypothetical answer of how you can do it: static

问题 I want to play a bit with the recently released Java 8 on OS X Mavericks, but have problems configuring the compiler compliance level to anything beyond 1.7 . I tried this with a recent Luna build (4.4.0M6) as well as with Kepler (4.3 SR2), patched with this. What am I doing wrong? 回答1: I think I got it right now. I just re-installed the patch from here and now 1.8 is shown as compiler level. I think while the "About" dialog showed me that the patch was installed, it probably wasn't done

问题 I have following 2 forms of calling a collect operation, both return same result, but I still cannot depend fully on method references and need a lambda. <R> R collect(Supplier<R> supplier, BiConsumer<R,? super T> accumulator, BiConsumer<R,R> combiner) For this consider the following stream consisting on 100 random numbers List<Double> dataList = new Random().doubles().limit(100).boxed() .collect(Collectors.toList()); 1) Following example uses pure lambdas Map<Boolean, Integer> partition =

问题 This question already has answers here : Printing debug info on errors with java 8 lambda expressions (1 answer) Reflection type inference on Java 8 Lambdas (5 answers) How to get the MethodInfo of a Java 8 method reference? (10 answers) Closed last year . I've been using a lot of method references and lambdas recently, and wanted to know at runtime if i could print to screen the source of the lambda ie its name, simply for debugging reasons. I figured it might be possible using reflection,