使用嵌套的for循环将1d数组转换为2d数组

Question

Im trying to scan a file and create a 1D array for each line, then immediately following the creation of that array copy into the first row of a 2D array. I've gotten my code to work for only the first row of the file. It won't move onto the next line. it copies the same line as it traverses the whole 2d array. i know that happens because the counter for the scanning the next line doesn't increase before it reaches the end of the 2d array. how can i increase the counter for scanning the next line? heres my code: (tempString is the 1D array already created before this loop)

    for(int i = 0; i < 7; i++){
        tempString = scnr.nextLine().split(" ");
        //add lines to 2d array
        for(int r = 0; r < 7; r++){
            int x = 0; //moves along each element in tempString
            for(int c = 0; c < tempString.length; c++){
                temp[r][c] = Double.parseDouble(tempString[x]);
                x++;
            }
        }
    }

Answer 1

You have 3 loops, but you only need two. Each input row read from the file will become a row of the 2-D array :

    for(int r = 0; r < 7; r++){
        tempString = scnr.nextLine().split(" ");
        temp[r] = new double[tempString.length];
        for(int c = 0; c < tempString.length; c++){
            temp[r][c] = Double.parseDouble(tempString[c]);
        }
    }

Answer 2

I am not quite sure with what exactly you need. But what I have derived from the question is that you have a file and you need to split it in a 2D array, in which the columns should contain the individual items within each line and each row should be in a new line.

My recommendation is to use ArrayList which will handle the dynamic lengths for you.

See the below example:

Say I have a file 'text.txt' which contains some data like this

abc def ghi
jhl mnop qrs uv
wx yz

Then here is a program which forms a 2D array, first dimension containing each row and the second dimension containing tokens from each line.

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

public class Split {
public static void main(String args[]){
    ArrayList<ArrayList<String>> columns = new ArrayList<ArrayList<String>>();

    columns.add(new ArrayList<String>());//Col 1
    columns.add(new ArrayList<String>());//Col 2
    columns.add(new ArrayList<String>());//Col 3

BufferedReader br = null;
try
  {
    br = new BufferedReader(new FileReader("src\\text.txt"));
    String sCurrentLine;
    int j=0;
    while ((sCurrentLine = br.readLine()) != null) {
    String sLine[] = sCurrentLine .split(" ");
    for(int i = 0; i < sLine.length; i++)
    {
        columns.get(j).add(sLine[i]);
    }
    j++;
    }
    for(ArrayList<String> line:columns){
        for(String tokens:line)
            System.out.println(tokens);
        System.out.println();
    }
  } catch (IOException ex) {
       ex.printStackTrace();
  }
}
}

If this is not what you need, please try to elaborate your question further if possible with examples.

Please note that I'm using spaces (" ") to split the tokens, you can replace it by anything that you are using.

I hope it helps :)