Java
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How to use java to convert UNIX epoch columns to dates in Apache spark dataframe?
I have a JSON data file that contains an attribute [creationdate], which is a UNIX EPOC of "long" numeric type The Apa…… -
If Java returns NoSuchElementException
How to create an IF statement to check whether the function returns "NoSuchElementException"? Similar to what I have b…… -
Java regular expressions do not delete points
I am trying to delete "..." in the text and replace it with "." My code: System.out.println(TextHandler.class.toString…… -
Java – unable to connect to Oracle using spring boot and Hibernate
I have a spring boot application using Postgres (1.2) Today, I was trying to switch it to Oracle, but when I tried to …… -
Java – check that the download manager has downloaded the file
How do I check if a file has been downloaded and run its installation? I have a code: public void downloadUpdate(Strin…… -
Special behavior of for loop in Java
Today, while reading boxing and automatic boxing, I came up with a scene and found that I was trapped in an infinite c…… -
JavaFX – set two ‘setonaction’ buttons to be the same
I get the EventHandler from another class. I want to set this EventHandler to the same button as other actionevents Is…… -
Are there any restrictions on log lines in Java – Travis build?
I can see our Travis CI build job until they record 10000 lines, and then the build seems to stop, no matter what stag…… -
Trying to get data from a web service in Java
[ [ { "title": "ginger","id": "38","product_id": "17","product_logo": "imagePath/Desert_0.jpg?itok=Uvm6nxp…… -
Using multiple array constructors in Java
There was a problem creating a constructor with multiple one-dimensional string arrays: class relation { String[] set…… -
Java uses “extend” and range resolution / point operators?
I have encountered this problem while reading some code, and I have no idea what it means I tried to use Google search…… -
Serializing classes using byte arrays in Java
I have a class with byte array in Java When I serialize and deserialize class objects, the value of the byte array is …… -
Java – serialization [replication] of lambda
See English answer > unable to deserialize lambda 2 I have two completely separate projects that contain a class It…… -
Java – write a program to round a number to the next multiple of 10 given the following conditions?
MyApproach I created two functions in the first function, and I calculated the sum of all four numbers In the second f…… -
Java – malformed JSON: unexpected ‘<' in spring
I want to make JSON from JPA @ entity. I have @Entity @JsonAutoDetect public class Bar implements Serializable { …… -
Java – what exactly is system out？
I've noticed that system. Net has never been initialized through a jar file launched from the command line (that is, t…… -
Use a Java stream to connect the elements of two collections with separators
I have two ways to say: ImmutableSet<String> firstSet = ImmutableSet.of("1","2","3"); ImmutableSet<String>…… -
Java – caching nested cacheable operations through spring cache
I was given the task of using spring cache for one of our services to reduce the number of database lookups When testi…… -
Java changes the number of worker threads
I'm using executorservice to create a fixed thread pool and start several working threads. These threads listen for wh…… -
Java – null and stringutils Differences between isblank()
I want to check whether a string is empty. I want to know which of the following is better, which is better and under …… -
How to use Jackson to serialize / deserialize Java util. stream. Stream？
Suppose I have the following objects public class DataObjectA { private Stream<DataObjectB> dataObjectBStrea…… -
java – Play Framework 2.4 Ebean
I was learning how to use ebean orm in the play framework, but I encountered an error Stockitem class: import com.avaj…… -
Java – pass the inline constructed class to the method as a class parameter
I need to call the following method void foo(Class<? extends Bar> cls); For the CLS parameter, I need to pass a …… -
Java – the way to invoke Android services in different threads. Is it still running on the main thread?
If I understand correctly, by default, Android services run on the main UI thread However, my problem is that if Servi…… -
Multithreading – JavaFX task Updatevalue triggers only the first change event
I want to observe the valueproperty of a task and take action when updatevalue () changes The change event seems to be…… -
Java – bitmap font reversal when using assetmanager
Today, I started using assetmanager in libgdx to load my assets Before that, I had loaded everything into a separate c…… -
Java – how do I get the next key from a specific key in the map?
I have something similar: Map< Integer,String> topology = new TreeMap< Integer,String>(); These include, f…… -
Why is “” marked for Java in sonarqube
In Java, I can convert int to string by "" intvalue Why is this inappropriate As far as I know, integer ToString (intv…… -
Java split – wrong length
Why do I receive a length of 3 instead of 4? How can I solve this problem to get the right length? String s="+9851452;…… -
JavaFX scrollpane – check the displayed components
I want to know if there is a scrollpane attribute in JavaFX 8 that can be used to listen for components currently disp…… -
General functions in Java
I'm not familiar with some general syntax in Java public static<T> T foo(T... a) Can anyone explain its meaning …… -
Java – HashMap that maintains the original key / value when entering duplicate keys
Can HashMap retain its original key / value pair when entering duplicate keys? For example, suppose I have something l……