java

问题 My database has numeric value, which is up to 256-bit unsigned integer. However, spark's decimalType has a limit of Decimal(38,18). When I try to do calculations on the column, exceptions are thrown. java.lang.IllegalArgumentException: requirement failed: Decimal precision 39 exceeds max precision 38". Is there any third-party library or workarounds that solve this issue? Or Spark is designed for numbers smaller than Decimal(38,18)? 来源： https://stackoverflow.com/questions/53074721/how-to-use

问题 I need to receive and save huge amount of data using spring data over hibernate. Our server allocated not enough RAM for persisting all entities at the same time. We will definitely get OutOfMemory error. So we need to save data by batches it's obvious. Also we need to use @Transactional to be sure that all data persisted or non was persisted in case of even single error. So, the question: does spring data during @Transactional method keep storing entities in RAM or entities which were

问题 I have tried all the sollutions in similar cases that I found, but with no luck. My jsp. <s:checkboxlist list = "positionsMap" listKey = "%{key.toString()}" listValue = "%{value}" name = "selectedPositions" value = "positionName" label = "Position" /> positionsMap is a Hashmap with key positionId and value positionName . selectedPositions is a list filled with the prechecked positions. Tested with debugger and has the correct value taken from database. positions is a list with id and name. So

问题 I have a ConstraintViolationException handler class that looks like this: @Produces @Singleton @Requires(classes = {ConstraintViolationException.class, ExceptionHandler.class}) public class ConstraintsViolationsExceptionHandler implements ExceptionHandler<ConstraintViolationException, HttpResponse> { @Override public HttpResponse handle(HttpRequest request, ConstraintViolationException exception) { return HttpResponse .status(HttpStatus.FORBIDDEN) .contentType(MediaType.APPLICATION_JSON)

问题 I've seen a Java RESTFUL webservice, that allowed the content-type to be requested in the URL with an extension at the end, such as .xml .json This is the style of content negotiation I am striving to achieve in my own Web Service. I am aware of the @Produces annotation, and the fact a method can resolve multiple types with the (value = {}) syntax, by adding an Accept header, say with Postman, the Chrome extension. But I'm not sure how to effectively extract out the information in one method,

问题 The title might be a bit misleading and might give you the impression this is an easy one so I will elaborate. I have a set of endpoints (REST services) that I want to secure without using the regular login way that Spring security provides. Usually you would first aim to the login endpoint (j_pring_security_check by default), authenticate and then send the request to the service endpoint along with the JSESSIONID. In this case i want to work without redirections. From the client-side I want

问题 I have a list of time zones that I want the user to choose from. So, I thought I can just call java.time.ZoneId.getAvailableZoneIds() and use the method getDisplayName on them. This results in a lot of duplicate entries like Central European Time Even if I add the time zone offset they are not unqiue. However, the ID of a ZoneId distinguishes the entries but how can I localize them ? The IDs are always in English like Europe/Rome 回答1: It's possible to get a localized version of the display

问题 When I change scenes on my stage with the following code, my stage changes size. However the button in the top right to maximize/minimize the windows says that the stage is still maximized even though it is clearly not. How am I able to keep the stage maximized when a scene change happens? import javafx.application.Application; import javafx.concurrent.Task; import javafx.geometry.Pos; import javafx.scene.Scene; import javafx.scene.control.Label; import javafx.scene.control.ScrollPane; import

问题 I need to connect to a server, which I know will be listening on a port. Although It could take some time to get operational. Is it possible to get ClientBootstrap to try to connect for a given number of tries or until a timeout is reached? At the moment, if the connection is refused, I get an exception, but it should try to connect in background, for example by respecting the "connectTimeoutMillis" bootstrap option. 回答1: You need todo it by hand, but thats not hard.. You could do something

问题 I am trying to find a sub- O(n) method to calculate the sum of an integer array ~~~(instead of iterating through 0 - n , I am doing it in n/2 )~~~ I'm still doing it in O(n) . public static int sum(int[] s) { int length = s.length - 1; int half = length/2; int sum = 0; for(int i = 0; i <= half; i++) { System.out.println(i + " " + s[i] + " + " + s[length - i]); sum += s[i] + s[length - i]; } return sum; } My algorithm works for even number of integers, however, when there are odd number of