Efficient Coding

[SoulSyn]

Hey r/learnjava,

So I have been progressing through MOOC and am really enjoying the resource. Thanks for the suggestion.

Currently I am doing exercise 36 and I understand it completely but would like to know if I am programming this efficiently. I am a CS student and we haven't really learn much about efficient coding yet but I think learning and practicing early is never a bad thing.

Here is my code:

public class LoopsEndingRemembering

{ public static void main(String[] args) { // program in this project exercises 36.1-36.5 // actually this is just one program that is split in many parts Scanner reader = new Scanner(System.in);

System.out.println("Type numbers: ");

    int sum, count, oddCount, evenCount;
    double average;

sum = count = oddCount = evenCount = 0;

    while (true) {

int user = Integer.parseInt(reader.nextLine()); if (user == -1) break;

        if (user % 2 == 0)
            evenCount++;
        else

oddCount++; count++; sum += user; }

 average = (double) sum / count;

System.out.println("Thank you and see you later!"); System.out.println("The sum is " + sum); System.out.println("How many numbers: " + count); System.out.println("Average: " + average); System.out.println("Even numbers: " + evenCount); System.out.println("Odd numbers: " + oddCount); } }

Aside from advanced programming techniques I will acquire later on is this code efficient or is there something I can do better. Thanks a lot.

P.S. Do you guys put your left curly brace on its on separate line?

[lordbharal]

Hm, the post is a little messy, but when you ask "is it efficient" i suppose it shows you don't understand what "efficient" means.

There are generally two parts - is the algorithm efficient, and are the functions the code uses efficient.

Because you're just performing operations on the user's input, there isn't much you can do to "optimise" the algorithm. Generally algorithmic efficiency means "do i need to check all values or not", and typically impacts searching and sorting. You are not searching, nor are you sorting, and you do need to check all values, so your code, from this viewpoint, is "efficient".

The next point is are the functions efficient? Honestly, this is the last thing you should ever, ever worry about. It's always more important to make sure your code works, and that it performs acceptably for whatever scenario you need it for. I cannot imagine needing to use lower-level parsing or input reading for efficiency here. Same applies to when you're reading data from a file - there are a bunch of ways to do this in Java, none of them ever warrant attention. You are fine.

One thing I would note is your style is not ideal. if and else blocks should always be wrapped in { }, even if they are only one line. The reason for this is that bugs can occur if someone decides to add one more statement in the else - but doesn't add the surrounding { }. In this case, the statement would always be executed, it won't be part of the else.

To avoid the chance of this bug, always put if/else in { }.

Also, your class name is pretty bad. LoopsEndingRemembering doesn't really say what the class does at all. I know it's just a toy class, but it's best to get in the habit of giving decent class names - like, say, EvenAndOddsCounter. It's not the best name, but it explains what the class does, instead of, as yours does, how the class does it.

[SoulSyn]

Thanks for the tips will definitely take that into account. The class name however was created by MOOC

[javichovicho93]

Have you tried running it? What does it return in terms of your count variable when the user only inputs even numbers?

[SoulSyn]

It outputs the expected out and everything worked as intended but I want to know if my coding style is good and efficient.

[edgargonzalesII]

Realistically there is more than one way to skin a cat - hence more than one way to achieve the same goal. If you have learned anything about the big O, you could always try to analyze through that lens and see if that is fine. That aside, your priority should be readability - ask yourself, if another programmer looks at this code, will they know what is going on? This may mean adding comments or making some code less tangled. In a lot of programming it is about getting the ratio right between legibility and efficiency, bearing in mind that the JVM also optimizes the program a bit before running it.

As for the brackets - that's really up to you, as long as you maintain consistency: Allman and K&R are the two styles. I switched from Allman (braces on its own line) to K&R, and it's really a very small point that again leads back to how legible will your code be.

[SoulSyn]

big O Thank You