this code is working fine for numbers 1 to 12 but after that its showing the wrong result can somebody explain ? package logicProgramming; import java.util.Scanner; public class Factorial { public …
Creating arrays for permutations within a subsection of a list
So I have a list: For each number that matches, I have to get every permutation of the identifier. The lists I would need from my example would be as follows: Steps I am taking currently to solve the problem: Read in the list, place each value in an array ([a][12]) and place that in an ArrayList I then find
Way to parseInt without try-catch in Java 8?
Is there a better way to try to convert to int a string that can be or not an integer? Integer.parseInt(String value) will work well with “25” or “019” but not with “hello” or “8A”. In Java 8, we have optional values, for example: You do not need to check nulls,…
How does Conditional annotation works in Spring Boot?
I understand that Spring Boot has lots of @Conditional annotations like, @ConditionalOnBean, @ConditionalOnClass, @ConditionalOnProperty, ConditionalOnWebApplication. But I do not know how this work? For Example: What I understood is, MyConfiguration will be loaded only if MyBean is available in my classpath.…
main ERROR Unable to locate appender “test” for logger config “test”
This is my log4j2 `JSON config when I use one file appenders it works fine. when I use two file appenders getting the error mention in the title.cant we add more than 1 file appenders. I don’t want to use a rolling file appender. Java code for creating logger variables Answer Try to define your appender…
Optaplanner – NullPointerException when creating jar file
My program works fine from my IDE (IntelliJ) but for some reason, when I try to create a jar file I get following error when I run the program from a terminal: Exception in thread “main” java.lang.NullPointerException at org.optaplanner.core.config.score.director.ScoreDirectorFactoryConfig.buildDr…
Spring Websocket STOMP: send RECEIPT frames
I have a Websocket-stomp server based on Spring and its SimpleBroker implementation (not utilizing an external broker). I would like to enable STOMP RECEIPT messages. How I could configure my code to send these automatically? Answer In Spring Integration test for the STOMP protocol we have this code: https://…
Apache POI Excel row color is only black and doesn’t change
I am trying to make excel files background one row white and other aqua color. But for some reason whatever I do the color always changes to black. It doesn’t change whatever I do, even if I try GREY_25_PERCENT its completely black. Here’s picture of my excel file Answer It may seem counterintuiti…
Are values returned by static method are static?
Please consider this code Will this static method return a new instance of MyClass every time it is called? or it is going to return a reference to the same instance over and over? Answer Lol lol lol Declaring a method static means it is a class method and can be called on the class without an instance (and c…
List view of concatenated lists
I want to create a list view that consists of the concatenation of a number of other lists. Example: What kind of technique and or pattern can I use in Java to fulfill these requirements? Details I want the concatenation to be lazy. (That’s the meaning of “view” in this context.) I want chan…