CODEWITHSUNDEEP
javamethods
Kyle W
Kyle W

Reputation: 37

Clarification on Mystery

I have just started taking a Computer Science class online and I am quite new to Programming(a couple of week's worth of experience). I am working on an assignment, but I do not understand what a mystery method is. I have yet to find an answer that I can wrap my head around online, in my textbook, or from my professor. Any explanation using this code as an example would also be greatly appreciated!

This is the equation where I saw it in:

public static void mystery1(int n) {
    System.out.print(n + " ");
    if (n > 0) {
        n = n - 5;
    }
    if (n < 0) {
        n = n + 7;
    } else {
        n = n * 2;
    }
    System.out.println(n);
}

If anybody can help, that would be amazing! Thank you!

Upvotes: 0

Views: 1525

Answers (3)

Ryan Shukis
Ryan Shukis

Reputation: 345

First of all, I voted your question up because I think it's a valid question for someone who is just beginning in computer programming, and I think that some people fail to understand the significance and purpose of Stack Overflow, which is to help programmers in times of need.

Secondly, I think that the couple of users that have commented on your post are on the right track. I have personally never heard of a mystery method, so I think the goal here is for you to simply figure out what the method does. In this case, the method takes a parameter for int 'n'. This means that if, at any point in the application, the 'mystery1()' method is called, an integer will have to be passed as the variable.

Let's say that a user enters the number '9'. The method would be called by the code mystery1(9). This would then run the first part of the 'if' statement, because n is greater than 0. So, n would be equal to n - 5, or 9 - 5, which is 4. (So, n=4.)

I hope my answer was somewhat helpful to you. Take care.

Upvotes: 2

Jon Egeland
Jon Egeland

Reputation: 12613

The point of this kind of exercise is that you are given a method, but they don't tell you what it does (hence the "mystery"). You are supposed to figure out what it does on your own (like "solving the mystery"). It doesn't mean that the method is special in any way.

Say I give you a "mystery" method like this:

public static void mystery(int n) {
  System.out.println(n+1);
}

You would "solve the mystery" by telling me that this method prints out the number that comes after n. Nothing else is special here.

In the example you gave, your job would be to tell me why the method prints out 0 0 when n = 0, or 6 2 when n = 6.

I think the usage of the term "mystery method" is rather misleading, as it has clearly made you (and many, many, many others) believe that something about these methods is special and something that you need to learn about. There isn't anything special about them, and there's nothing to learn.

I think a lot of people would understand this better if instructors just said "tell me what this method does" instead of trying treat students like 5 year olds by saying "Here's a mystery method (ooh, fancy and entertaining). Can you play detective and solve the mystery for me?"

Upvotes: 1

Josh Chappelle
Josh Chappelle

Reputation: 1588

Your assignment is probably to figure out what this method does. More specifically, what does it print to the screen. I'll walk you through how to figure this out.

You have a function, also called a methood, called mystery1. A function is just a named block of code that you can use throughout other pieces of code. This function takes an integer argument called n. Let's assume n=12 for this example.

The first thing that happens in your function when it is called is that n is printed out via the System.out.print method. Notice that it prints a blank space after it. Notice also at the end it prints another value of n that gets assigned within the method. So the method is going to print "12 ?" without the double quotes. The question mark is what we have to figure out. The code says if n > 0 then n = n-5. Since 12 is greater than 0, n gets the new value of 7. The next if statement says if n is less than 0, n gets assigned n+7. But it is not less than zero, it is 7 at this point, so we move to the else statement. In this statement n gets multiplied by 2 which is 14. So the last statement prints 14.

So for an input value of 12 this method prints: 12 14

I hope this helps. If not, please give more detail about your assignment and what you don't understand about my explanation.

Upvotes: 2

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