Liutauras Vilda

Stephan van Hulst wrote: static record SignumCounts(long negativeCount, long zeroCount, long positiveCount) {}  static SignumCounts countSignums(Collection<? extends Number> numbers) {    var counts = numbers.stream().map(Number::intValue).collect(groupingBy(Integer::signum, counting()));    return new SignumCounts(counts.get(-1), counts.get(0), counts.get(1));  }

Nice. With one assumption. It would fail with inputs such as: List.of(); List.of(-1); List.of(0); List.of(1) and pairs of them.

Carey Brown wrote:I was thinking of something more preemptive.
private static void incrementValues(int x) {    // WARNING: Do not remove "int whatever =" or it won't compile.    // It is required to convert the expression into a statement.    int whatever = (x > 0) ? positives++: (x == 0) ? zeroes++: negatives++; }

To write an unnecessary stuff to bypass compiler doesn't sound right, primarily semantically, that introduces a necessity to write comment out of nowhere.
I'd not write any comment here, and would not use this construct at all for the same reason.

What I mentioned earlier to Anil, I registered yesterday to hackerank to check the problem at hand and I couldn't see in the provided template any static variables. So I'm not sure where they came from. I solved that problem by using collector to collect results and then did printing them out (didn't use any static variables), and I'd suggest Anil to refactor his code too.

Anil, you mentioned you are doing those exercise to prepare for an interview. Now, those interviews may differ in many ways, some of those are just to solve problem and bypass some auto grader tool. Some coding challenges might be, that in addition to passing an auto grader, someone is going to review your code for its elegancy. Some interviews might be, that they don't care much about solution end-to-end, but rather a journey to it, how you decompose problem, what's your thinking process behind, how you name variables, whether you solve it in a disciplined manner and similar.. So try to be a best version of yourself when solving them, not just get unit tests to pass.

Anil Philip wrote:In the code sample, they are static instance variables.

I registered to that platform and I couldn't find them. You are asked to implement plusMinus() function that returns nothing, it should just print result as requested. I've passed the tests with my almost original code. I didn't know about ratios.

Here is perhaps slightly less verbose approach:
List<Integer> numbers = List.of(-5, -4, -3, -2, -1, 0, 0, 1, 2, 3, 4, 5); Function<Integer, Result> f = n -> (n > 0)        ? new Result(1, 0, 0)        : (n == 0)        ? new Result(0, 1, 0)        : new Result(0, 0, 1); List<Result> results = numbers.stream().map(f).toList();
I've omitted other parts that are in the earlier post.

Anil Philip wrote:How would I do it as part of the lambda in the stream?

Most likely there are many ways to do it, you never said what though. But with a bit of guessing and trying to keep close to what you have, here is a way which first came to my mind:
import java.util.List; public class Test {    public static void main(String[] args) {        List<Integer> numbers = List.of(-5, -4, -3, -2, -1, 0, 0, 1, 2, 3, 4, 5);        List<Result> results = numbers.stream().map(n -> {            int positives = 0;            int zeroes = 0;            int negatives = 0;            if (n > 0) {                positives++;            } else if (n == 0) {                zeroes++;            } else {                negatives++;            }            return new Result(positives, zeroes, negatives);        }).toList();        int countOfPositives = results.stream().mapToInt(Result::positives).sum();        int countOfZeroes = results.stream().mapToInt(Result::zeroes).sum();        int countOfNegatives = results.stream().mapToInt(Result::negatives).sum();    } } record Result(        int positives,        int zeroes,        int negatives ) { }
I'm sure there are way more elegant ways of achieving the same.

Anil Philip wrote:I don't know why the compiler complains about the ternary operator: "not a statement".

Well, the problem is not a ternary operator, but rather an expression not being a statement (expression itself is fine though). It has to be a statement at that point in your code.

So you have to do something with it in order to have a statement, eg.:
int result = (x > 0) ? positives++: (x == 0) ? zeroes++: negatives++;or
System.out.println((x > 0) ? positives++: (x == 0) ? zeroes++: negatives++);
Expression on its own is not a statement. There are kind of expressions that also can be used as statements if they are followed by semicolon, and I had to look it up in JLS to see how they are officially called, so it is expression statement, eg.:
positives++;So that ^ can stay as a loose line.

kevin Abel wrote:in 1979

At that time I had no business on this planet.

Campbell Ritchie wrote:Please supply more information

Indeed.

@OP
I have Study Guide books for OCA and OCP (thanks to Jeanne), but those are for Java 8. Chapter 1, review question 6 looks intact to me, but it doesn't talk about any "distance".

Not even clear to me whether you suggest it is an errata or your guess as correct answer for aforementioned review question.

Welcome to the Ranch and have a quantumful joyful time. Maybe with one or two tricky questions..

David Bush wrote:Are you telling me BlueJ can handle standard Oracle Java?

Yes. I just downloaded (and installed) most recent version of BlueJ and tried to write some primitive multithreaded app - works as expected.

David Bush wrote:The introduction to BlueJ says this was initially a language created by a PhD student, which grew into an IDE.

The language was called Blue. BlueJ (with J) is not a language, but an IDE.

David Bush wrote:I don't find "thread" anywhere in the BlueJ pdf document.

That's because it isn't a BlueJ thing. BlueJ is an IDE, or let's simplify it - a one of text editors that could be used to write Java programs. The concept you are referring to is part of Java language.

Note down k9s, this is the tool I couldn't live without lately. You may or may not need it, but you asked for useful.

Matthew Henry wrote:shortcuts useful for developers

It may look most useful cmd + c / cmd + v (windows: ctrl + c / ctrl + v), but it isn't, so don't use it.