将文件中的数据加载到2D数组中

Question

The file in question is formatted as such

1 1 1 1 1 1 1 1 
1 0 0 0 0 0 0 1 
1 0 0 0 0 0 0 1 
1 0 0 0 0 0 0 1 
1 0 0 0 0 0 0 1 
1 1 1 1 1 1 1 1 

And I need a way to parse it into an array like this

    int[][] array = {{1, 1, 1, 1, 1, 1, 1, 1},
                     {1, 0, 0, 0, 0, 0, 0, 1},
                     {1, 0, 0, 0, 0, 0, 0, 1},
                     {1, 0, 0, 0, 0, 0, 0, 1},
                     {1, 0, 0, 0, 0, 0, 0, 1},
                     {1, 1, 1, 1, 1, 1, 1, 1}};

So far I have worked this much out

        BufferedReader reader = new BufferedReader(new FileReader(fc.getSelectedFile()));
        String line = null;
        int[][] myArray;
        while ((line = reader.readLine()) != null){
            myArray = new int[6][8];
            for(int y = 0; y < myArray.length; y++)
                for (int x = 0; x < myArray[y].length; x++){

                    myArray[y][x] = Integer.parseInt(line);
                    loadedArray[y][x] = myArray[y][x];
                }
        }

And it is throwing an Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: "1 1 1 1 1 1 1 1 " Me and 2D arrays never really got along...

Answer 1

行也从6开始并增加-这将导致索引超出范围错误，因为您将无法访问该值。

Answer 2

You seem to know the number of lines before you read the file. Therefore there's no need to recreate the array every time you read the line. Simply parse line by line and start the index with 0.

package test2.newpackage;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Arrays;

public class NewMain {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new FileReader("data/test.txt")); // replaced with my test file here
        String line;
        final int rows = 6; // row count never changes
        int[][] myArray = new int[rows][];
        int currentRow = 0;
        while ((line = reader.readLine()) != null && !line.isEmpty()) {
            // System.out.println(line); // write file content to System.out just to be sure it's the right file
            String[] nums = line.trim().split(" "); // remove spaces at both ends of string before splitting
            int[] intLine = new int[nums.length];
            myArray[currentRow++] = intLine;
            for (int col = 0; col < nums.length; col++) {
                int n = Integer.parseInt(nums[col]);
                intLine[col] = n;
            }
        }
        reader.close();
        System.out.println(Arrays.deepToString(myArray));
    }

}

However, if you don't know the number of rows in advance, use a List<int[]> , eg ArrayList<int[]> instead of int[][] . You can still convert to an array after you finished parsing.

Update:

Since you seem to have spaces at the end of each line, trim before splitting:

Change

String[] nums = line.split(" ");

to

String[] nums = line.trim().split(" ");

Edit:

Maybe your last line containing digits ends with a newline character. Just to make sure you don't read a 7th line that contains only a empty string, I added a check for empty lines.

Edit 2:

Since you still have a problem, I changed the code to exactly the code I used. (I hardcoded the file).

Since that really isn't a radical change to the previously posted code, I can only guess the source of the error:

• You didn't properly recompile and use really use an old version of the program or
• The only digits in your input file are 1 s or
• Your file choosing mechanism is erroneous and you actually get a different file than you think.

You could check, if content of the file that is read is what you think it is by uncommenting the line printing in the outer loop.

Answer 3

I see a few problems:

1. You're getting IndexOutOfBounds because you increment rows when it's already the size of the array.

2. You should count the number of lines in the file before creating the 2D array

    int rows = 0; while (reader.readLine() != null) rows++; 

3. Have a separate counter for the current row

4. You set myArray to a new matrix every iteration of the loop. Set it once and just add to it in the loop.

---

int rows = 0, 
    cols = -1;
String line = null;

// Count number of rows and columns
while ((line = reader.readLine()) != null) {
    rows++;
    if(cols == -1) cols = line.split(" ").length(); // only set once
}

// Pretty sure you can't read lines anymore, so close and recreate reader
reader.close();
reader = new BufferedReader(new FileReader(fc.getSelectedFile()));

final int[][] myArray = new int[rows][cols];

// Iterate over every row
for(int row = 0; (line = reader.readLine()) != null; row++){
    String[] nums = line.split(" ");

    for (int col = 0; col < cols; col++) {
        myArray[row][col] = Integer.parseInt(nums[col]);            
    }
}

reader.close();