从网格将数字导入2D数组Java

Question

So just a quick question here, I have done some work with file reading but not enough to be proficient with it. I have a grid:

10 14 81 34 76

18 22 64 4  87

1  6  42 13 15

4  32 21 87 31

7  42 24 20 15

(just an example grid)

I have it in a text file currently. How do I input each number into its own place on a 2D array, seems simple but with my limited knowledge I have been unable to do it!

Answer 1

Assume first you know the size. first step is to do file reading. create a bufferreader

BufferedReader br=new BufferedReader(new FileReader(path));

Then loop through this reader

int[][] result=new int[rownum][columnnum];
int i =0;
While(br.ready()){
    String line=br.readline();
    String[] tokens=line.split(" ");
    // now put each in 2D array
   for(int j=0;j<tokens.length;j++){
        result[i][j]=Integer.parseInt(tokens[j]);
    }
    i ++;
}

If you don't know the size then in that loop you put in ArrayList. Then use toArray method

Answer 2

Well , Its pretty logical .

Let's breakdown your grid ,

1. It is space delimited
2. Consider each line to be a row of a 2D array.

Here's some code ,

    File file = new File("test.txt");
    FileReader fileReader = new FileReader(file);
    BufferedReader bufferedReader = new BufferedReader(fileReader);
    ArrayList<String> lines = new ArrayList<String>();
    String line;
    while ((line = bufferedReader.readLine()) != null) {
        lines.add(line);
    }
    fileReader.close();

Now the ArrayList lines has all your lines from the textfile. All you have to do now , is iterate throught it with a simple for loop and extract the values.

String [] singleline = lines.get(0).split(" "); // this array contains all integers at line 0 .

just parse it to an integer value and add it to your 2D array in any way you prefer .

 ArrayList<Integer> singleLineIntegers = new ArrayList<Integer>();
 for(i=0;i<temp.length;i++)
 singleLineIntegers.add(Integer.parseInt(temp[i]));

Now this singleLineIntegers array Contains all the integers in line 1 , use the lines array to repeat this and insert it into your 2d array.