Splitting a CSV file of coordinates into longitude and latitude ArrayLists

Question

I have a CSV file that contains a bunch of coordinates. In the file, the coordinate pairs are split up by commas. I have already split the pairs up and placed them into a ArrayList of strings. Now, I am trying to split each pair up into their respective longitude and latitude ArrayLists. So essentially, I am trying to use the .split() function twice (splitting the coordinates into pairs, the splitting the pairs into longitude and latitude values) and I am struggling to figure out how to use split the second time. I am not sure exactly what I am doing wrong or what the correct syntax is to accomplish this. I am working in Java. Here is what I have tried:

Path countyCoords = Paths.get("countyCoords.txt");
File coordsData = countyCoords.toFile();
    
FileReader frCoords = null;
BufferedReader brCoords = null;
    
ArrayList<String> coordsList1 = new ArrayList<>();
    
ArrayList<String> longitude = new ArrayList<>();
ArrayList<String> latitude =  new ArrayList<>();
    
try {
    frCoords = new FileReader(coordsData);
    brCoords = new BufferedReader(frCoords);
        
    String lineReader = brCoords.readLine();
    
    while (lineReader != null) {
        System.out.println("Coords: "+lineReader);
        String[] threeLine = lineReader.split(",");
        String[] values = threeLine.split(" ");
        coordsList1.add(threeLine);
        String lon = values[0];
        String lat = values[1];
            
        longitude.add(lon);
        latitude.add(lat);
            
        lineReader = brCoords.readLine();
    }
} catch (IOException ex) {
    System.err.println("Error: "+ex.getMessage());
} finally {
    try {
        if (brCoords != null) {
            brCoords.close();
        }
    } catch (IOException ex) {
        ex.printStackTrace();
        System.exit(0);
    }
}

Answer 1

Assuming your data in the format 1 2, 3 4, 5 6

The following snippet can be used to process a line from the data file. I omit exception handling, resources closing.

String line = brCoords.readLine();
String[] coords = line.split(",");
for(String c : coords) {
  String[] lonLat = c.split(" ");
  longitude.add(lonLat[0]);
  latitude.add(lonLat[1]);
}