Populating three different arrays from the contents of a file that has three columns of integers.

Question:

I am looking for a way to populate three different arrays from the contents of a file that has three columns of integers.

Answer:

Scanner(), StringTokenizer() and Integer.parseInt()

Code:

import java.io.*;
import java.util.*;  
 
public class ScanFileContents {
 
   public static void main(String[] args)throws IOException {
 
      String[] columns = new String[3];
 
      Scanner input;
      String str;
      StringTokenizer tokens;
 
      // need to know ho big of an array to create 
      int lines = 0;
      input = new Scanner(new File("data.txt"));
      while(input.hasNext()){
         str = input.nextLine();
         lines = lines+1;
      }
      input.close();
 
      int[] row1 = new int[lines-1];
      int[] row2 = new int[lines-1];
      int[] row3 = new int[lines-1];
 
      input = new Scanner(new File("data.txt"));
      str = input.nextLine();
      tokens = new StringTokenizer(str);
      columns[0]=tokens.nextToken();
      columns[1]=tokens.nextToken();
      columns[2]=tokens.nextToken();
 
      int count = 0;
      while(input.hasNext()){
         str = input.nextLine();
         tokens = new StringTokenizer(str);
         row1[count] = Integer.parseInt(tokens.nextToken());
         row2[count] = Integer.parseInt(tokens.nextToken());
         row3[count] = Integer.parseInt(tokens.nextToken());
         count = count + 1;
      }
      System.out.println(columns[0] + ":" + Arrays.toString(row1));
      System.out.println(columns[1] + ":" + Arrays.toString(row2));
      System.out.println(columns[2] + ":" + Arrays.toString(row3));
   }
}

Output:

$ java ScanFileContents
TOM:[100, 77, 100, 89, 91, 95, 84, 92]
BOB:[65, 78, 89, 66, 75, 78, 82, 93]
JOHN:[33, 98, 44, 86, 85, 68, 44, 100]

$ cat data.txt
TOM BOB JOHN
100 65 33
77 78 98
100 89 44
89 66 86
91 75 85
95 78 68
84 82 44
92 93 100