需要帮助，使Java方法可以从文本文件中创建2D字符串数组

Question

I've been trying to make a function in Java that will read a text file that has "1" and 0"s like this

11000000001111111110
11111000000000011000
11111111000000001000
11111100000000001100
11111000000000011110
11111000000000111111
11111110000000001111
11111111110001111100
11111000000000001111
11000000000000000000
10000000000000000000
00000000001100000000
00000000011110000000
10000000011000000000
11000000000000000000

and then convert the "1"s to a certain character or image and the "0"s to another character/image. I'm hoping to use this for an ASCII-graphic game I've been planning on. However, I keep on getting the

java.lang.ArrayIndexOutOfBoundsException: 1

error on my Eclipse console. Below is the code for the function.

public static String[][] create2DStringMatrixFromFile(String filename) throws Exception {
    String[][] map = new String[20][15];
    for (int x = 0; x < 20 ; x++) {
        for (int y = 0; y < 15; y++) {
            map[x][y] = "0";
        }
    }

File inFile = new File(filename);
Scanner in = new Scanner(inFile);
in.close();

in = new Scanner(inFile);

int lineCount = 0;
while (in.hasNextLine()) {
  String[] currentLine = in.nextLine().trim().split("\\s+"); 
     for (int i = 0; i < 15; i++) {
        map[lineCount][i] = currentLine[i];
     }
  lineCount++;
 }                                 
 return map;

}

It would be greatly appreciated if someone could point out what I did wrong :)

EDIT: I took into consideration of what @andrewdleach has suggested me to do and this is my code now.

    public static String[][] create2DStringMatrixFromFile(String filename) throws IOException {

    File inFile = new File(filename);
    BufferedReader reader = new BufferedReader(new FileReader(inFile));

    String[][] map = new String[20][15];
    //Arrays.fill(map, "0");
    //fill each row with 0
    for (String[] row : map) {
        Arrays.fill(row, "0");
    }
    int rowCount = 0;
    while (reader.ready()) {
        parseLine(reader.readLine(), rowCount, map);
        rowCount++;       

    }
    reader.close(); // might delete later
     return map;
}

private static void parseLine(final String theLine, final int theCurrentRow, String[][] map) {
     final char[] eachColumn = theLine.toCharArray();
     int curColumn = 0;
     for (char c : eachColumn) {
         map[theCurrentRow][curColumn] = new String(Character.toString(c));
         curColumn++;       
     }

 }

However now I get this error whenever I run it.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 15
at com.trees.Map.parseLine(Map.java:62)
at com.trees.Map.create2DStringMatrixFromFile(Map.java:50)

I spent the past hour or so trying to fix it, but I couldn't figure it out. Any tips, please? If I can't get this to work with Arrays, I might rewrite it with ArrayLists as someone else mentioned, which might work out better.

Answer 1

Well, harcoding your variables is always a bad thing. It doesn't allow you flexibility should the size of the expected array change.

Your error Array Index Out of Bounds is commonly referred to as an off-by-1 error, so if you sift through your code you'll probably find a place where you're trying to access an indexed portion of the 2D array that's not actually declared.

All that being said, to solve your problem you may want to consider tackling it like so:

public static String[][] create2DStringMatrixFromFile(String filename) {

    File inFile = new File(filename);
    BufferedReader reader = new BufferedReader(new FileReader(inFile)));

    String[][] map = new String[20][15];
    Arrays.fill(map, "0");

    int rowCount = 0;
    while (reader.ready()) {
        parseLine(reader.readLine(), rowCount);
        rowCount++;       

    }                                
     return map;
}


private void parseLine(final String theLine, final int theCurrentRow) {
     final char[] eachColumn = theLine.toCharArray();
     int curColumn = 0;
     for (char c : eachColumn) {
         map[theCurrentRow][curColumn] = new String(c);
         curColumn++;       
     }

 }

Answer 2

Calling split("\\\\s+") does not split the value "11000000001111111110", since the value doesn't contain any spaces.

This means that currentLine is an array with one element, the un-split value, hence currentLine[i] will fail for i = 1 .