java-8

问题 I think title describes the problem. Here's some code: import static org.junit.Assert.assertEquals; import java.lang.annotation.*; public class Main { public static void main(String[] args) throws Exception { assertEquals("foo", Main.class.getDeclaredMethod("myMethod").getAnnotation(Anno.class).param()); // the magic here -> set to bar assertEquals("bar", Main.class.getDeclaredMethod("myMethod").getAnnotation(Anno.class).param()); } @Anno(param = "foo") public void myMethod() {} @Retention

问题 I think title describes the problem. Here's some code: import static org.junit.Assert.assertEquals; import java.lang.annotation.*; public class Main { public static void main(String[] args) throws Exception { assertEquals("foo", Main.class.getDeclaredMethod("myMethod").getAnnotation(Anno.class).param()); // the magic here -> set to bar assertEquals("bar", Main.class.getDeclaredMethod("myMethod").getAnnotation(Anno.class).param()); } @Anno(param = "foo") public void myMethod() {} @Retention

问题 This question already has answers here : Java reflection: How can I retrieve anonymous inner classes? (2 answers) Closed 2 years ago . I know Class.getDeclaredClasses() can obtains all the classes that it has declared but doesn't including anonymous classes. I'd like to know is there a way to get all the enclosed classes via the enclosing class ? for example, I want to get the all enclosed classes defined in Root for test purpose. class Root{ void run(){ Runnable task = new Runnable(){ public

问题 This question already has answers here : Java reflection: How can I retrieve anonymous inner classes? (2 answers) Closed 2 years ago . I know Class.getDeclaredClasses() can obtains all the classes that it has declared but doesn't including anonymous classes. I'd like to know is there a way to get all the enclosed classes via the enclosing class ? for example, I want to get the all enclosed classes defined in Root for test purpose. class Root{ void run(){ Runnable task = new Runnable(){ public

问题 new File(url).lastModified() returns a long equal to the number of milliseconds since the epoch, which is GMT-based. What is a simple way to convert this to a String representing system-local date/time? If you really need to see an attempt from me here it is but it's a terrible mess and it's wrong anyway: LocalDateTime.ofEpochSecond(new File(url).lastModified()/1000,0,ZoneOffset.UTC).atZone(ZoneId.of("UTC")).format(DateTimeFormatter.ofLocalizedDateTime(FormatStyle.LONG)) Beyond LocalDateTime

问题 I have a Map: Map<String, String> utilMap = new HashMap(); utilMap.put("1","1"); utilMap.put("2","2"); utilMap.put("3","3"); utilMap.put("4","4"); I converted it to a String: String utilMapString = utilMap .entrySet() .stream() .map(e -> e.toString()).collect(Collectors.joining(",")); Out put: 1=1,2=2,3=3,4=4,5=5 How to convert utilMapString to Map in Java8? Who can help me with? 回答1: Split the string by , to get individual map entries. Then split them by = to get the key and the value. Map

问题 I have a Map: Map<String, String> utilMap = new HashMap(); utilMap.put("1","1"); utilMap.put("2","2"); utilMap.put("3","3"); utilMap.put("4","4"); I converted it to a String: String utilMapString = utilMap .entrySet() .stream() .map(e -> e.toString()).collect(Collectors.joining(",")); Out put: 1=1,2=2,3=3,4=4,5=5 How to convert utilMapString to Map in Java8? Who can help me with? 回答1: Split the string by , to get individual map entries. Then split them by = to get the key and the value. Map

问题 I was trying out the following example provide in the talk to understand the tail recursion in java8. @FunctionalInterface public interface TailCall<T> { TailCall<T> apply(); default boolean isComplete() { return false; } default T result() { throw new Error("not implemented"); } default T get() { return Stream.iterate(this, TailCall::apply).filter(TailCall::isComplete) .findFirst().get().result(); } } Utility class to use the TailCall public class TailCalls { public static <T> TailCall<T>

问题 I was trying out the following example provide in the talk to understand the tail recursion in java8. @FunctionalInterface public interface TailCall<T> { TailCall<T> apply(); default boolean isComplete() { return false; } default T result() { throw new Error("not implemented"); } default T get() { return Stream.iterate(this, TailCall::apply).filter(TailCall::isComplete) .findFirst().get().result(); } } Utility class to use the TailCall public class TailCalls { public static <T> TailCall<T>

问题 I do have a simialar problem like descripted here. But with two differences first I do use the stream api and second I do have an equals() and hashCode() method already. But within the stream the equalitity of the of Blogs are in this context not the same as defined in the Blog class. Collection<Blog> elements = x.stream() ... // a lot of filter and map stuff .peek(p -> sysout(p)) // a stream of Blog .? // how to remove duplicates - .distinct() doesn't work I do have a class with an equal