java-programming | Java programming repository for batch | Batch Processing library

I understand that it's a bad practice to import * and it's best to import what exactly we need explicitly. However, I'm curious why importing util.* does not include util.stream.*.

If I import java.util.stream.*;

this piece of code works successfully:

How do I center my buttons both vertically and horizontally?
I can't get it to work, whatever Pane or Vbox i use.

I want to create something like this :

My output right now is this :

Here is my stage :

I've been going through this MOOC.fi Java course and got to the problem about developing a selection sort algorithm on this page (https://java-programming.mooc.fi/part-7/2-algorithms). I don't have the solutions, so I was wondering if anyone here could help me solve this problem. Basically, I got through all the steps uptil Part 4, but when I tried to make the selection sort method, my method only sorted the numbers correctly until it got to the second to last number, and then it started switching the numbers incorrectly. Can anyone look over my code and tell me where I went wrong?

Since there is no traditional loop in Kotlin (as per this article), how would you write a for loop in Kotlin that loops n times, or specifically, zero times if n is zero?

The equivalent in Java would be

I want to scrape the media files of a specific website that has notes in it. I tried many times to download the notes from it and it was really easy to get the files but none of them were in order. The website is likely to make an Ajax call after you scroll to page 30 and then next 30 pages load up and it goes on like this until the end of pages. Can someone please give me a direction how to get the files in the correct order ? I know the question isn't sufficient enough but I just want a general idea about how to solve this issue.

I am dropping the website for reference https://lecturenotes.in/m/37320-note-for-java-programming-java-by-prateek-jain?reading=true

I have seen some question in Java (question 15 here), printing the value of f gives value as false

Doing the exercise 'Literature' on https://java-programming.mooc.fi/part-10/2-interface-comparable I discovered a very strange behavior when trying to sort key-value pairs in a HashMap, without copying anything to a TreeMap. I was supposed to add books, by making a Book class and adding them to a List. However I wanted to try without making a new class, so opted for the HashMap. My code was as follows:

I'm doing the Mooc course and it's teaching us how to compare objects from made up classes like "Person" and see if they are equal to each other. They give us the following code:

I came across this question :

How can we identify whether a compilation unit is class or interface from a .class file?

The answer given was "from java source file header", with explanation

The Java source file contains a header that declares the type of class or interface, its visibility with respect to other classes, its name and any superclass it may extend, or interface it implements.

But I didn't find anything explaining how source file header dictates class or interface in any standard documentation. Wikipedia says following about the magic number (which I found to be relevant) in the class file:

CAFEBABE became the class file format, and CAFEDEAD was the persistent object format.

Can someone point me to document explaining in detail how class file tells whether it's for class or interface along with other details of class file?