Recent Posts
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Java — on doubles and equality
I have a method that returns a double When I tested this method as part of JUnit, I noticed the following oddities: St…… -
Apply the function to each nth element in the vector
I have a vector in R: > v <- c(5,10,15,20,25,30,35,40,45,50) I want to apply a function to every Nth element of …… -
Java – what does “J” mean in a JApplet?
翻译错误 Invalid Access Limit Solution When sun started working on swing, they were like javax swing. Something like a…… -
How to judge the efficiency of Java code
I just realized that from a computational point of view, I don't know how to judge whether a piece of Java code is val…… -
Java – use list Multiple use of size () or variable? (local optimization)
I have a simple function called many In this function, I have many call list sizes (including about 10 elements): list…… -
Loop problem in Java
What is the error in the following code? while ((char t==(char) system.in.read())!='0') Solution You cannot declare a …… -
Java – find the size of the file in the gzip file
Is there any way to find out the size of the original file in the gzip file in Java? As in, I have a 15 MB file a.txt,…… -
Java – many methods that cover many classes in one class
public class EventController extends MouseAdapter implements ActionListener { public class EventController extends Mou…… -
Java Rest framewok
Which is a good java rest framework? I want it to be deployed with Tomcat 6 Solution See my answer: Restful web develo…… -
Java thread pool
I want to learn how to write a thread pool in Java Can anyone point out my useful resources? Solution You can view the…… -
How to handle Boolean values in Java through bitwise operators
Consider this example int i=11,j=5; boolean b=true,c=false; System.out.println(b&c); // --> output=false System…… -
Java – cannot run Hello world on drools – kiecontainer does not select DLR files from the classpath
The following documents: 6.1 The basics I created a simple class applicant, which should be checked by using the DRL f…… -
Java – ArrayList removeall() does not delete objects
I have simple ArrayLists for member classes: ArrayList<Member> mGroupMembers = new ArrayList<>(); ArrayLis…… -
Java – find the smallest integer based on the input
I have a task to find the minimum, maximum and average number of user input Basically, they enter positive integers, s…… -
Java regular expression performance
I'm trying to parse links with regular expressions in Java But I think it's getting too slow For example, to extract a…… -
Java 8 avoids a large number of if / else statements
I have something that looks like this: public boolean isValidObject(SomeObject obj){ if(obj.getField() == null){ …… -
Is the result of mathematical operation on Java – double completely repeatable?
I have a complex data processing algorithm, using java 8 and double as the data type Given the same input (hundreds of…… -
Java – Method println (int) in printstream type is not applicable to parameters (string, int, int, int)
public static void main(String[] args) { public static void main(String[] args) { int num1 = 1; int num2 = 1; …… -
Java – scanner class hasnextline infinite loop
Why does this code enter an infinite loop when I try to give it a basic text file? import java.io.File; import java.io…… -
String operation in Java
I asked the following two questions in an interview yesterday 1 GT; Given a string, calculates a new string in which a…… -
Java – Oracle – pool connected to spring framework
We are trying at @ L_ 301_ Implement Oracle connection pool with the help of 0 @ framework We are using the DBCP conne…… -
Dynamic array in Java
What I want to do is ... int sum[]; ... for(int z.....){ ... sum[z] = some_random_value; ... } But it gives a…… -
Failed: metadata error: Java Lang.runtimeexception: unable to instantiate org apache. hadoop. hive. metastore. HiveMetaStoreClient
I closed my HDFS client while HDFS and hive instances were running Now, when I re-enter hive, I cannot perform any DDL…… -
Java – JPA / eclipse link – retrieve column names
I'm trying to update my java knowledge because I was last in 1.4 When used in version x... I'm trying to use 1.6 0, es…… -
Java – MD5 is the letter of each password worth it?
to greet, I am currently developing a project involving login system, which aims to set up as safely as possible What …… -
JavaFX Maven plug-in and API are incompatible
I recently upgraded my java version to 7u40. 0 on my Fedora 19 Then I started to make a nasty mistake in the JavaFX pr…… -
Use the string comparison in Java again
Novice problem, but I have this Code: import java.util.*; import java.io.*; public class Welcome1 { // main meth…… -
Short condition, Java
I want to test whether the current char is', ',' – ',' Or‘‘ if((current != ' ') || (current != '.') || ...) Any ideas?…… -
Java – how to get parameters from the URL in Liferay portlet?
I used something like feed in Liferay 6 JSP of out of the box portlet such as jspf: String articleId =null; HttpServle…… -
Java – abstract classes cannot be implemented from other packages
For some reason, I can't seem to implement an abstract class outside the package that defines it Abstract classes in P…… -
Java – when comparing two equal integers in a while loop, does the equal operator fail?
I post two examples below Example 1: Integer myVar1 = 42985; Integer myVar2 = 1; while (true) { if (myVar2 …… -
Java generic problem
Can I write a method that can create an instance of any specified type? I think Java generics should help, so it might……