I want to read in a grid of numbers (n*n) from a file and copy them into a multidimensional array, one int at a time. I have the code to read in the file and print it out, but dont know how to take each int. I think i need to splitstring method and a blank delimiter "" in order to take every charcter, but after that im not sure. I would also like to change blank characters to 0, but that can wait!
This is what i have got so far, although it doesnt work.
while (count <81 && (s = br.readLine()) != null)
{
count++;
String[] splitStr = s.split("");
String first = splitStr[number];
System.out.println(s);
number++;
}
fr.close();
}
A sample file is like this(the spaces are needed):
26 84
897 426
4 7
492
4 5
158
6 5
325 169
95 31
Basically i know how to read in the file and print it out, but dont know how to take the data from the reader and put it in a multidimensional array.
I have just tried thi开发者_如何学运维s, but it says 'cannot covernt from String[] to String'
while (count <81 && (s = br.readLine()) != null)
{
for (int i = 0; i<9; i++){
for (int j = 0; j<9; j++)
grid[i][j] = s.split("");
}
Based on your file this is how I would do it:
Lint<int[]> ret = new ArrayList<int[]>();
Scanner fIn = new Scanner(new File("pathToFile"));
while (fIn.hasNextLine()) {
// read a line, and turn it into the characters
String[] oneLine = fIn.nextLine().split("");
int[] intLine = new int[oneLine.length()];
// we turn the characters into ints
for(int i =0; i < intLine.length; i++){
if (oneLine[i].trim().equals(""))
intLine[i] = 0;
else
intLine[i] = Integer.parseInt(oneLine[i].trim());
}
// and then add the int[] to our output
ret.add(intLine):
}
At the end of this code, you will have a list of int[]
which can be easily turned into an int[][]
.
private static int[][] readMatrix(BufferedReader br) throws IOException {
List<int[]> rows = new ArrayList<int[]>();
for (String s = br.readLine(); s != null; s = br.readLine()) {
String items[] = s.split(" ");
int[] row = new int[items.length];
for (int i = 0; i < items.length; ++i) {
row[i] = Integer.parseInt(items[i]);
}
rows.add(row);
}
return rows.toArray(new int[rows.size()][]);
}
EDIT: You just updated your post to include a sample input file, so the following won't work as-is for your case. However, the principle is the same -- tokenize the line you read based on whatever delimiter you want (spaces in your case) then add each token to the columns of a row.
You didn't include a sample input file, so I'll make a few basic assumptions.
Assuming that the first line of your input file is "n", and the remainder is the n x n integers you want to read, you need to do something like the following:
public static int[][] parseInput(final String fileName) throws Exception {
BufferedReader reader = new BufferedReader(new FileReader(fileName));
int n = Integer.parseInt(reader.readLine());
int[][] result = new int[n][n];
String line;
int i = 0;
while ((line = reader.readLine()) != null) {
String[] tokens = line.split("\\s");
for (int j = 0; j < n; j++) {
result[i][j] = Integer.parseInt(tokens[j]);
}
i++;
}
return result;
}
In this case, an example input file would be:
3
1 2 3
4 5 6
7 8 9
which would result in a 3 x 3 array with:
row 1 = { 1, 2, 3 }
row 2 = { 4, 5, 6 }
row 3 = { 7, 8, 9 }
If your input file doesn't have "n" as the first line, then you can just wait to initialize your final array until you've counted the tokens on the first line.
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