java-8

问题 I wish to implement the Stream<E> interface (I admit, it's the unnecessarily large one) and add a builder method foo() . public MyStream<E> implements Stream<E>, ExtendedStream<E> { private final Stream<E> delegate; public MyStream(final Stream<E> stream) { this.delegate = stream; } // a sample Stream<E> method implementation @Override public <R> MyStream<R> map(Function<? super E, ? extends R> mapper) { return new MyStream<>(this.delegate.map(mapper)); } // the rest in the same way (skipped)

问题 I'm open to use a lib. I just want something simple to diff two collections on a different criteria than the normal equals function. Right now I use something like : collection1.stream() .filter(element -> !collection2.stream() .anyMatch(element2 -> element2.equalsWithoutSomeField(element))) .collect(Collectors.toSet()); and I would like something like : Collections.diff(collection1, collection2, Foo::equalsWithoutSomeField); (edit) More context: Should of mentioned that I'm looking for

问题 This question already has answers here : Is it possible to cast a Stream in Java 8? (4 answers) Closed 4 years ago . I have a list of objects: List<SomeType> myList; I want to get a list of sub-types available in this list: List<SomeChildType> myChildList = myList.stream().filter(e -> e instanceof SomeChildType).collect(??????) I don't know how to collect to obtain the correct list type. 回答1: You need to cast the objects: List<SomeChildType> myChildList = myList.stream() .filter(SomeChildType

问题 I have an Instant coming from a source that should, according to the spec, be a LocalDate, but don't see any methods in LocalDate for the conversion. What is the best way to do this? 回答1: LocalDate.ofInstant(...); I believe was added in Java 9. LocalDateTime has that method in Java 8. yourInstant.atZone(yourZoneId).toLocalDate(); Will work with earlier versions for LocalDate... 回答2: Other answers provided the mechanics for the transformation, but I wanted to add some background on the meaning

问题 This question already has an answer here : How to handle upper or lower case in JSR 310? [duplicate] (1 answer) Closed 4 years ago . I'm trying to parse date time string to LocalDateTime. However if I send month with all caps its thorwning an error, is there any workaround. Here is the below code @Test public void testDateFormat(){ DateTimeFormatter formatter= DateTimeFormatter.ofPattern("dd-MMM-yyyy HH:mm:ss"); LocalDateTime dateTime = LocalDateTime.parse("04-NOV-2015 16:00:00", formatter);

问题 I've been struggling with selenium to fix this issue: java.lang.NoSuchMethodError: org.openqa.selenium.support.ui.Wait.until(Lcom/google/common/base/Function;)Ljava/lang/Object; This is where I get this error: Wait<WebDriver> wait = new FluentWait<>(getDriverInstance()) .withTimeout(timeout, TimeUnit.SECONDS) .pollingEvery(frequency, TimeUnit.SECONDS) .ignoring(NoSuchElementException.class); wait.until(driver -> { assert driver != null; elt.click(); return true; }); The most solutions on the

问题 I have a method: invokList(List<Object> list); This method is inside a jar and I have no access to the source code of it. So for that, I need to execute the invokList in a parallel way, can someone help for this? The idea is to split the list to many lists and execute invokList in parallel. I have made this example: import java.util.Arrays; import java.util.Collections; import java.util.List; public class Test { public static void main(String[] args) { List<Integer> list = Arrays.asList(1,2,3

问题 This question already has answers here : Java switch statement: Constant expression required, but it IS constant (13 answers) Closed 4 years ago . I was working on switch case. If we use class.getName(), then, I am getting error that "case expressions must be constant expressions" as follows: switch(param.getClass().getName()) { case String.class.getName(): // to do break; } Even if we do following, take string class name in a constant, then also, getting same error: public static final

问题 This question already has answers here : Java switch statement: Constant expression required, but it IS constant (13 answers) Closed 4 years ago . I was working on switch case. If we use class.getName(), then, I am getting error that "case expressions must be constant expressions" as follows: switch(param.getClass().getName()) { case String.class.getName(): // to do break; } Even if we do following, take string class name in a constant, then also, getting same error: public static final

问题 This question already has answers here : Java switch statement: Constant expression required, but it IS constant (13 answers) Closed 4 years ago . I was working on switch case. If we use class.getName(), then, I am getting error that "case expressions must be constant expressions" as follows: switch(param.getClass().getName()) { case String.class.getName(): // to do break; } Even if we do following, take string class name in a constant, then also, getting same error: public static final