Thread: .txt file won't convert to ints

Heya! I'm having trouble converting a .txt file to ints and storing them in an array. All variables not seen have been properly initialized. Initially, I was getting an error message similar to the one below, but instead, it was the � (unidentified character) you see in one of the .replaceAll statements. I think the issue is happening during the code's attempt at parsing the string, and for some reason, it's saying that the null space can't be converted into an int, when it should just skip over it (it's not even a space, it's just null). Any clue as to what I should do would be greatly appreciated. Thanks!


Here's the error:

Exception in thread "main" java.lang.NumberFormatException: For input string: ""
at java.base/java.lang.NumberFormatException.forInputString(Num berFormatException.java:67)
at java.base/java.lang.Integer.parseInt(Integer.java:646)
at java.base/java.lang.Integer.parseInt(Integer.java:778)
at tile.TileManager.loadMap(TileManager.java:86)
at tile.TileManager.<init>(TileManager.java:30)
at main.GamePanel.<init>(GamePanel.java:41)
at main.Main.main(Main.java:20)


"at tile.TileManager.loadMap(TileManager.java:86)" is referencing this line:

nums[col] = Integer.parseInt(String.valueOf(line.charAt(col))) ;

Anything errors below this one are irrelevant, as it's just tracing how the class got called.

public void loadMap() {
 
		//try {
			InputStream is = getClass().getResourceAsStream("/maps/map0001.txt"); //imports the text file
			Scanner scnr = new Scanner(is); //lets us read the contents of the text file
 
			int col = 0;
			int row = 0;
 
 
			while(row < gp.maxScreenRow) { //loops through all rows coordinates
 
 
				while(scnr.hasNextLine()) { //checks if the scanner has anything to read, if so, it reads that line, stores it in mapTileNum and increments row
 
 
					String line = scnr.nextLine();//stores a scanned line in the String "line"
					line = line.replaceAll(" ","");//removes all spaces
					line = line.replaceAll("�","");//removes all unknown characters
					if(line.equals("")) {
						continue;
					}
					//String[] numbers = new String[gp.maxScreenCol];//creates a new String array that will store all of the numbers in a given row
					int[] nums = new int[gp.maxScreenCol];//all of the Strings in numbers will be converted to ints and stored here
 
 
					while(col < line.length()) {//goes through all characters (actually numbers, not yet parsed) of line
 
 
 
						nums[col] = Integer.parseInt(String.valueOf(line.charAt(col))); //uses col to get a specific value from the map, and .parseInt changes it from a string to an Integer
 
						mapTileNum[col][row] = nums[col]; //stores the extracted value in the equivalent place in a 2d array
						col++;
 
					}
 
					/*for(int i = 0; i < numbers.length; i++) {
					String replacement = numbers[i].replace(" ", "");
					numbers[i] = replacement;
					}*/
 
					row++;
				}
 
			}
 
			scnr.close();
		/*}catch(IOException e) {
			e.printStackTrace();
		}*/
	}

Exception in thread "main" java.lang.NumberFormatException: For input string: ""
at java.base/java.lang.NumberFormatException.forInputString(Num berFormatException.java:67)
at java.base/java.lang.Integer.parseInt(Integer.java:646)
at java.base/java.lang.Integer.parseInt(Integer.java:778)
at tile.TileManager.loadMap(TileManager.java:86)
at tile.TileManager.<init>(TileManager.java:30)
at main.GamePanel.<init>(GamePanel.java:41)
at main.Main.main(Main.java:20)


"at tile.TileManager.loadMap(TileManager.java:86)" is referencing this line:

nums[col] = Integer.parseInt(String.valueOf(line.charAt(col))) ;

What are the values in the variables used in line 86? What is in line and what is in col?
Add a print statement before line 86 that prints out those two variables' values.

The error message says an empty String was passed to the parseInt method.
Is the text of that message correct? Was there a space between the ""s?

Did you print out the values of line and col as I suggested?
What was printed?

it's a null value.

Note: a null value is NOT the same as an empty String: ""

Where is the col=0 value printed? What was the value in line?
Add this statement to the code after the statement that assigns a value to line:

   System.out.println("col="+ col + ", line=" + line + "<");

Also print out the value of num[col] after the assignment statement that gives it a value is executed.

Can you add the print statements, compile and execute the code, copy the print out and paste it here?

Also post the code with the print statements so I can see where they are located.

What are these values shown in the printout?
47
0
0
The print statement should have a small String before the value that is printed so you know what it is the value of. Like you did here:
System.out.println("col="+ col + ...

The following ordering of the print statements would be better:

				       System.out.println("line="+line);
 
 
					while(col < line.length()) {//goes through all characters (actually numbers, not yet parsed) of line
 
						System.out.println("col="+col + ", char=" + line.charAt(col));
 						nums[col] = Integer.parseInt(String.valueOf(line.charAt(col))); //uses col to get a specific value from the map, and .parseInt changes it from a string to an Integer
 
 						System.out.println("nums[col]=" + nums[col]);  // show after value assigned
 
						mapTileNum[col][row] = nums[col]; //stores the extracted value in the equivalent place in a 2d array
						col++;
 
					}

Also many of the comments in the code are too long and are not needed.
For example the comment on this line is not needed; the code is self explanatory
x = x + 2; // add 2 to x
However this comment would be better, it says why the 2 is being added:
x = x + 2; // Skip over 1 element in the array

--- Update ---

Why is this text:

Exception in thread "main"

before the col=0
and not before

java.lang.NumberFormatException: For input string: ""

--- Update ---

The purpose of the printouts is to see if any of the text is being parsed to an int.
col starts at 0 and then increments. Does it ever get to 1?
What is stored in the nums array? Its initial value is 0.

Does the input txt file use UTF16 encoding?
If so, the constructor for the Scanner class needs to be told that:

      Scanner scnr = new Scanner(is, "UTF16");                 //<<<<<<< needs charset Name

The byte pattern in the before printout:

line before .replaceAll=��1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1<

shows two ? at the start of the line followed by alternating chars and "spaces".
I recognize this as the pattern for a UTF16 file.

Here is the printout as bytes of a UTF16 file. Notice the first two bytes are not ASCII characters
and that following those 2 bytes are 2 byte pairs of ASCII values and 0s. See doc for UTF16
The file contains the String "1234" '1' has an int value of 49

      System.out.println((int)'1'); //  49
 
      InputStream is = new FileInputStream(new File("TestUTF16.txt"));
      byte[] bytes = new byte[10];   // read first 10 bytes of file here
      is.read(bytes);
      is.close();
      System.out.println(Arrays.toString(bytes));  // [-1, -2, 49, 0, 50, 0, 51, 0, 52, 0]