How do i get characters in a file into a 2D array in Java?

Question

So i have a file that looks like this:

+-+-+-+ ("/n")
|S|   | ("/n")
+ + + + ("/n")
|   |E| ("/n")
+-+-+-+ ("/n")

/n being a new line in the file

and i want to have each character here as an entry in a 5x7 array. I do not know how to do it, this is what i have tried (along with a lot of other things. input is the file):

public static void main(String[] args) throws FileNotFoundException {

  Scanner input = new Scanner(new File("maze0.txt"));

  char maze[][] = new char[5][7];
  int charCount = 0;
     for (int row = 0; row < finalHeight; row++) {
        for (int col = 0; col < finalWidth; col++) {
           while (input.hasNextLine()){
               String line = input.nextLine();
              if ((row < finalHeight - 1 || col < finalWidth) && charCount < line.length()) {
                     maze[row][col] = line.charAt(charCount);
                     charCount += 1;
                     System.out.print(maze[row][col]);

But this prints out +S+ + which is not right. I am a brand new beginner programmer and having a hard time with this, thanks for any help you can offer.

I fixed it!! this is what I did:

  Scanner input = new Scanner(new File("maze0.txt"));




  char maze[][] = new char[5][7];
  input.nextLine();
     for (int row = 0; row < 5; row++) {
        String fileLine = input.nextLine();
        for (int col = 0; col < 7; col++) {
              char nextChar = fileLine.charAt(col);
              maze[row][col] = nextChar;
              System.out.print(maze[row][col]);

gallickgunner · Answer 1 · 2016-02-05T06:08:55.007

Convert the line to character array using .toCharArray() That will give you an array of all the characters. Then just feed them into your array.

it'd look something like..

// everytime we come to a new row, read a line from the file, convert it into letters then proceed on feeding them into columns.
for (int row = 0; row < finalHeight; row++) 
{
      String line = input.nextLine();
      Char[] chars = line.toCharArray();
      if(!input.hasNextLine())
            break;            // if there is no more lines to read, break the loop.
      for (int col = 0, i = 0; (col < finalWidth && i < chars.length); col++,i++) 
      {
        maze[row][col] = chars[i];
        System.out.print(maze[row][col]);
      }
}

score 0 · Answer 2 · answered Feb 05 '16 at 05:29

Actually, while the screen might display +S+ +, you only have one value in your array - at maze[0][0] (a value of '+'). Your while loop reads the entire file before the for loops ever increment.For each line it reads, it sets maze[row][column] = line.charAt(charCount); -- but row and column never get incremented because, well, there's another line to read. So it reads another line and overwrites maze[0][0] to be the line.charAt(1) (because you incremented charCount). This character is the space. Then it loops back through because there's another line to read, and puts the 3rd character at maze[0][0]. So on and so forth. When it's read the entire file, then it steps through the for loops, but while (input.hasNextLine()) doesn't execute because it's already read the entire file.

oh ok that makes sense! I was having a hard time seeing what the loop was really doing with the while loop in there. Thank you! — pootyy, Feb 05 '16 at 06:10

adiSuper94 · Answer 3 · 2016-02-05T06:00:13.247

0

you just need two loops why are you running 3 loops?

Scanner sc = new Scanner(new File("maze.txt"));
String line = null;
for(int i = 0; i< 5;i++)
{
      line = sc.readLine()
      for(int j = 0; j < 7; j++)
      {
          maze[i][j] = line.charAt(j);
      }
}

This snippet should read the file and store it in a matrix.

Since you are reading the line in the inner loop, you are printing the diagonal.

edited Feb 05 '16 at 06:00

answered Feb 05 '16 at 05:29

adiSuper94

23
10

score 0 · Answer 4 · answered Feb 05 '16 at 05:30

Here is a simple and efficient way to do it.

public static void main(String[] args) throws FileNotFoundException {
    Scanner input = new Scanner(new File("maze0.txt"));

    char maze[][] = new char[5][7];
    for (int i = 0; i < maze.length; i++) {
        //Get each line and convert to character array.
        maze[i] = input.nextLine().toCharArray();
    }
}

score 0 · Answer 5 · answered Feb 05 '16 at 05:34

You can read each line from the file and convert it to char array.

public static void main(String[] args) throws IOException {
    Scanner scan = new Scanner(new File("maze0.txt")); 
    String b;
    char maze[][] = new char[5][7];
    for (int row = 0; row < 5; row++) {
        while ( scan.hasNextLine() ){
            b = scan.nextLine();
            maze[row] = b.toCharArray();
            System.out.println(maze[row]);
        }
    }    
    scan.close();
}

score 0 · Answer 6 · answered Feb 05 '16 at 06:27

import java.io.*;
import java.util.*;

public class B 
{
    public static void main(String...aaadf)throws FileNotFoundException
    {

        Scanner sc = new Scanner(new File("D://maze.txt"));
        char maze[][] = new char[5][7];
        String line = null;
        for(int i = 0; i< 5;i++)
        {
              line = sc.nextLine();
              for(int j = 0; j < 7; j++)
              {
                  maze[i][j] = line.charAt(j);
              }
        }
        for(int i = 0; i< 5;i++)
        {

              for(int j = 0; j < 7; j++)
              {
                  System.out.print(maze[i][j]);
              }
              System.out.println();
        }
    }
}

you should provide a small explanation for your code. – Michael Feb 05 '16 at 06:35 — Michael, Feb 05 '16 at 06:35

How do i get characters in a file into a 2D array in Java?

6 Answers6

Linked