java-stream

I want to perform certain operation on first element of my list and different operation for all remaining elements. Here is my code snippet: List<String> tokens = getDummyList(); if (!tokens.isEmpty()) { System.out.println("this is first token:" + tokens.get(0)); } tokens.stream().skip(1).forEach(token -> { System.out.println(token); }); Is there any more cleaner way to achieve this preferably using java 8 streaming API. Holger One way to express the intention is Spliterator<String> sp = getDummyList().spliterator(); if(sp.tryAdvance(token -> System.out.println("this is first token: "+token)))

As for example, there are two lists: List<Double> list1 = Arrays.asList(1.0, 2.0); List<String> list2 = Arrays.asList("one_point_zero", "two_point_zero"); Using Stream, I want to create a map composed of these lists, where list1 is for keys and list2 is for values. To do it, I need to create an auxiliary list: List<Integer> list0 = Arrays.asList(0, 1); Here is the map: Map<Double, String> map2 = list0.stream() .collect(Collectors.toMap(list1::get, list2::get)); list0 is used in order list1::get and list2::get to work. Is there a simpler way without creation of list0? I tried the following code

The Stream.flatMap() operation transforms a stream of a, b, c into a stream that contains zero or more elements for each input element, e.g. a1, a2, c1, c2, c3 Is there the opposite operations that batches up a few elements into one new one? It is not .reduce(), because this produces only one result It is not collect(), because this only fills a container (afaiu) It is not forEach(), because this has returns just void and works with side effects Does it exist? can I simulate it in any way? Finally I figured out that flatMap is its own "inverse" so to say. I oversaw that flatMap not necessarily

Since a few versions, IntelliJ has a very helpful feature: when you put the individual method calls of a stream() statement on separate lines, IntelliJ puts type information on each line: But when you don't call stream() directly, like when it is returned from another method, that information is omitted: Is there a way to convince IntelliJ to show such type information for such situations, too? As pure text, with manually inserted comments to "show" the problem with pure text: public Stream<Entry<String, String>> withTypeInformation() { return generateMap() // Map<String, String> .entrySet() /

try (Stream<String> lines = Files.lines(targetFile)) { List<String> replacedContent = lines.map(line -> StringUtils.replaceEach(line,keys, values)) .parallel() .collect(Collectors.toList()); Files.write(targetFile, replacedContent); } I'm trying to replace multiple text patterns in each line of the file. But I'm observing that "\r\n"(byte equivalent 10 and 13) is being replaced with just "\r"(just 10) and my comparison tests are failing. I want to preserve the newlines as they are in the input file and don't want java to touch them. Could anyone suggest if there is a way to do this without

The following snippet of code counts the number of files in a directory: Path path = ...; .... long count = 0; try { count = Files.walk(path).parallel().filter(p -> !Files.isDirectory(p)).count(); } catch (IOException ex) { System.out.println(ex.getMessage()); } The code above fails to get the number of files, if an exception is thrown. The question is: How do I ignore the exception and continue counting the number of files. In Java 7 : I have used Files.walkFileTree(path, utils) , with the following class: public class Utils extends SimpleFileVisitor<Path> { private long count; @Override