ArrayList size resetting to 1 in a for loop-CodePudding

I am trying to find the index of a value in a nested ArrayList, but I need to find the position of the first ArrayList. I am receiving an error when I run this code:

public int findCity(String city) {
  city = "\""   city   "\"";
  System.out.println(cityArray.size());
  for (List<String> value : cityArray) {
    String newCity = value.get(1); 
    if (newCity == city) return cityArray.indexOf(value);
  }
  return -1;
}

The problem happens in the line after the for loop:

String newCity = value.get(1);

It's telling me that index 1 is out of bounds for length 1. Any help is greatly appreciated!

I found the problem: I was using nextLine() to read the csv file, and it was creating a new array every time there was a space. This was a huge oversight on my part, but now I can start fixing the problem.

Once again, sorry for the inconvinience.

CodePudding user response：

You're mixing up cityArray.size() and cityArray.get(1).size(), which can be completely different.

(You are also comparing strings with ==, which is likely to cause disaster. Use .equals.)

CodePudding user response：

i think the problem is that you start counting from 1, but an ArrayList starts counting from 0. This is why the index is out of bounds.

You could try this:

String newCity = value.get(0);

CodePudding user response：

Below code can help you ,though I did not understand your problem.

public static void main(String[] args) {
        List<String> list1 = Arrays.asList(new String[]{"A","B"});
        List<String> list2 = Arrays.asList(new String[]{"Y","Z"});
        List<List<String>> cityArray = new ArrayList<>(2);
        cityArray.add(list1);
        cityArray.add(list2);
        System.out.println(findCity("Z", cityArray));
    }

    public static int findCity(String city, List<List<String>> cityArray) {
        System.out.println(cityArray.size());
        for (List<String> value : cityArray) {
            for(String newCity :value) { 
                if (newCity.equalsIgnoreCase(city)) {
                    return cityArray.indexOf(value);
                }
            }
        }
        return -1;
    }