Reading from a file to a bidimensional array

[Frank Ramirez]

Hello everybody
I'm working on a project for school and part of it is to read from a txt file and convert to a bidimensional array.
Here is the code we created for that:

import java.io.*;


public class Main {

    private static char[][] maze;
    private static String readFile = " ";
    private static int numRows = 0;
    private static int numCols = 0;
    
    public static void main(String[] args) throws FileNotFoundException, IOException{
        


        setArraySize(readFile);

        populateArray(readFile);
        

    }

    public static void setArraySize(String file) throws FileNotFoundException, IOException
    {
        //open the file
        FileReader freader = new FileReader("maze.txt");
        BufferedReader inputFile = new BufferedReader(freader);

        

        //Reading the first line
        readFile = inputFile.readLine();

        //get the number of columns
        numCols = readFile.length();

        //While is reading the file to know the number of colums and rows
        while (readFile != null)
        {
            //System.out.println(readFile);
            readFile= inputFile.readLine();
            //to get size
            numRows ++;
        }

        //close file
        inputFile.close();
    }

    public static void populateArray(String file) throws FileNotFoundException, IOException
    {
        //Creating an array to hold the data
        maze=new char[numRows][numCols];

        //open the file
        FileReader freader = new FileReader("maze.txt");
        BufferedReader inputFile = new BufferedReader(freader);

        
        for(int i=0; i< numRows; i++)
        {
            //Reading the first line
            readFile = inputFile.readLine();

            for(int j=0; j< numCols; j++)
                System.out.print(maze[i][j] = readFile.charAt(j));
            System.out.println();
        }

        //close file
        inputFile.close();
    }
}

As you can see, we created a method to determine the size of the array (specially the number of rows) and another method to populate the array.
What bothers me is that we have to read the file twice, once for each method.
Is there a way that I can combine both so I read the file only once?

Thank you in advance

[Darryl Burke]

Read the file into a List<List<String>> or a List<String[]>, if you know in advance how many columns are contained in each row -- you'll probably want to use the ArrayList implementation of List -- then after populating the list, if you really need a bidimensional array you can generate it using List#toArray. But you probably shouldn't need that, it would be better to refactor your code to use the List<List> or List<String[]> instead.