Accessing Elements from an ArrayList in JavaFX [duplicate] - arraylist

Question

This question already has answers here:
Can we use index like array index to access List<T>?
(7 answers)
Closed 6 years ago.
The ArrayList that I'm using is in a method that returns the ArrayList, but it's not recognizing the ArrayList in start. How do I access the elements from an ArrayList vs. a regular array, and is it returning the ArrayList from the method properly? Thanks!
try
{
ArrayList<Integer> scores = loadFile("scores.txt");
}catch(FileNotFoundException e)
{
System.err.println("File error: " + e.getMessage());
}catch(IOException e)
{
System.err.println("IO error: " + e.getMessage());
}
GridPane root = new GridPane();
primaryStage.setScene(new Scene(root, 600, 600));
//linePane();
//textPane();
Circle circle = new Circle();
circle.setRadius(1.0f);
for(int i = 0; i < 59; i++)
{
double polar = (double)(scores[i]);
private static ArrayList<Integer> loadFile(String filename) throws IOException
{
int numberOfRecords = 0;
Scanner fin = new Scanner(new File(filename));
ArrayList<Integer> scores = new ArrayList();
while(fin.hasNext())
{
scores.add(fin.nextInt());
numberOfRecords++;
}
Collections.sort(scores);
return scores;
}

Answer 1

You get a value from an Arraylist not by scores[index], but with a desginated method.
scores.get(i);
------------- EDIT -----------------
The code isn't recognizing scores since it's outside of its scope.
ArrayList <Integer> scores = null;
try{
scores = //code
} catch {}
if(scores != null){
scores.get(i);
}
-------------------- EDIT -------------------
Second question: the Polyline.
The add method of Polyline takes in a Double not an Integer (scores is an ArrayList of Integers). Therefore, cast it as a Double.
line.getPoints().add((double)scores.get(i));
Your other question about Invocation Error. It is thrown because of Illegal Argument Exception you have in the method "line". Basically, you are adding the same Node to the root too many times.
private static void line(){
Polyline line = new Polyline();
for(int i = 0; i < 59; i++)
{
line.getPoints().add((double)scores.get(i));
}
root.getChildren().add(line); // <- outside of the for loop
}