How can I create a List with sorted Strings and a specific Integer in Java?

Question

Hay there, I need to create a list for a project with amount of terms for this method but it kind of didn't work as I thought. The "term"-names also have to look like this and have been sorted in the form of "Term:1", "Term:2",..., "Term:amount". If amount should be negative I have to return an empty list. I tried the following:

public static List <String> createTerms(int amount){
List <String> termNames = new ArrayList<String>();
    if (amount>0){
        termNames.add(amount,"Term:"+amount);
        Collections.sort(termNames);
        return termNames;
    }else
        return Collections.emptyList();
}

Sam · Accepted Answer · 2021-03-18 20:17:56Z

1

Even though this is tagged as JavaScript, this looks like Java. Take a look at the ArrayList documentation. Here is the method for add():

add(int index, E element)

Where it adds element to the structure at index. So it doesn't work the way you assumed in your code. If you would like to use ArrayList, even though I would advise against and suggest you use something like Map, found here, I would suggest you use a for-loop to add the terms in. So instead of:

 termNames.add(amount,"Term:");
 Collections.sort(termNames);

You can just do:

  if (amount > 0){
      for (int i = 0; i < amount; i++) {
          String element = "Term: " + (i + 1);
          termNames.add(element);
      } 
      return termNames;
  }

Also, I am a bit confused about your logic. Shouldn't the prompt be that you should return an empty list if amount < 0? Can you clarify a bit if my answer doesn't answer your question?

edited Mar 18, 2021 at 20:17

answered Mar 18, 2021 at 20:12

Sam

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2 Comments

Ben Over a year ago

Hello Sam, thank you very much for your answer! The prompt should return an empty list if the amount was < 0! I misstyped there (already edited it) Your answer did solve my question :) I am still not too fond of lists and maps, but I am really greatful for the answer. Especially the part with String element = "Term: " + (i + 1); So thanks again and have an especially nice day!

Holger Over a year ago

The if (amount > 0) check is unnecessary. Since the loop’s condition is i < amount and the initial value of i is zero, the desired behavior of producing an empty list for zero and negative amounts is already implied.

MrFrizziee · Accepted Answer · 2021-03-18 19:52:04Z

0

termNames will only ever have 1 element since the list is declared within the scope of the function. You should consider another data structure such as a dictionary for this implementation and make sure it's a global variable if you intend to fill it with more than 1 element

Edit: You should change to tag from Javascript to Java to ensure you receive correct advice

answered Mar 18, 2021 at 19:52

MrFrizziee

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1 Comment

Ben Over a year ago

Thank you for the advice :) And I changed the tag

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