Question

I need to parse a .txt file to three double arrays. This files has various lines. In each line there are three integes divided by space.

Example:

19.1    24.3    0
18.2    24.0    0
12.6    24.9    20
14.4    28.0    20

My goal is to get three double array (x, y and z) and in each array there should be a column. So the result should be the same of writing the following instructions:

double[] x = {19.1,18.2,12.6,14.4};
double[] y = {24.3,24.0,24.9,28.0};
double[] z = {0,0,20,20};

I know how to open and read files, something like this:

String file = "filename.txt";
String line=null;
FileReader fr = new FileReader(file);
BufferedReader br = new BufferedReader(fr);
while(!(line=br.readLine()).contains("EOF")) {
  // read and process one line..
}

What I don’t know how to do is how to parse each number of the current line and assign it to one of the three vectors.

Answer 1

You can simply split and parse each line as follows:

String[] row = line.split("\\s+");
double d1 = Double.parseDouble(row[0]);
double d2 = Double.parseDouble(row[1]);
double d3 = Double.parseDouble(row[2]);

Also, if the number of lines is not fixed then it will be easier and makes more sense to use ArrayLists of Doubles instead of arrays of doubles.