Elements not adding to the arraylist

Question

I recently started using ArrayLists instead of Arrays, so i wrote a simple program that should change all teh positive integers in an array to 1, negative to -1 and all the 0's to 0. Now I don't know why but my code isn't working, could you please point me to the right direction since I am not yet experienced with ArrayLists? Here is my code:

private static ArrayList<Integer> ja = new ArrayList<Integer>();
private static String j = null;
private static void keskmine() {
    System.out.println("Please enter an array of integers:");
    j = sc.nextLine();
    ArrayList<String> bitsj = new ArrayList<String>(Arrays.asList(j.split(",")));
    for(int i = 0; i < bitsj.size(); i++){
        ja.add(Integer.parseInt(bitsj.get(i).trim()));
    }
    for(int i = 0; i < ja.size(); i++){

        if(ja.get(i) > 0){
            ja.set(i, 1);
        }if(ja.get(i) < 0){
            ja.set(i, -1);
        }else{
            ja.set(i, 0);
        }
    }
    System.out.println(ja);
}

Thank you in advance!

EDIT: I am so sorry, I forgot to post half that I intended to! For example if I am giving my program an input "1, 1, 1" It outputs 0, 0, 0 but it should output "1, 1, 1" and it does that to whatever I enter.

"isn't working" doesn't tell us anything about what you expect to see or what you actually see. Please provide a short but complete program demonstrating the problem, ideally not requiring user input, and specifying what you expect to happen vs what's happening. — Jon Skeet
– Jon Skeet, Commented Oct 5, 2014 at 20:23
Have you heard of the for (<Type> element : <list>) syntax? — bcsb1001
– bcsb1001, Commented Oct 5, 2014 at 20:31

herrlock · Accepted Answer · 2014-10-05 20:26:42Z

2

in this check

if(ja.get(i) > 0){
    ja.set(i, 1);
}
if(ja.get(i) < 0){
     ja.set(i, -1);
}else{
    ja.set(i, 0);
}

an else is missing. correct it to

if(ja.get(i) > 0){
    ja.set(i, 1);
} else if(ja.get(i) < 0){
     ja.set(i, -1);
} else {
    ja.set(i, 0);
}

you are currently first checking, if the number is greater than 0. after that you always check, if the number is smaller than 0.

eg: you have a 42:
check if > 0 => entry set to 1
after that: check if < 0 => false, so set to 0

answered Oct 5, 2014 at 20:26

herrlock

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1 Comment

Artur Over a year ago

And that just solved it! I thought something was messed up when I was splitting the ArrayList but it was just this else if... Thank you for your help!

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