Reading in a file with BufferedReader, using Tokenizer for adding into an adjacency matrix

[mayumi yamada]

Hello,

I am having trouble adding numbers read from a file with BufferedReader, using Tokenizer to split the numbers up by " " - space and adding them to an adjacency matrix.
Thanks for your help in advance!

Below is the text file and my code, that I have at the moment.

0 1 0 0 1 1 0 0
1 0 0 0 0 1 1 0
0 0 0 1 0 0 1 0
0 0 1 0 0 0 0 1
1 0 0 0 0 1 0 0
1 1 0 0 1 0 0 0
0 1 1 0 0 0 0 1
0 0 0 1 0 0 1 0

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.StringTokenizer;
  
public class Foo
{
  @SuppressWarnings("null")
public static void main(String[] args) throws Exception
  {
    String line, token = null, delimiter = " ";
    StringTokenizer tokenizer;
    BufferedReader input = null;
    int adjMatrix [][] = null;
    int node = 0;
    String filename = "sample.txt";
    input = new BufferedReader(new FileReader(filename));
    line = input.readLine(); // when printed gives first line in file
  
    // outer while (process lines)
    while (line != null)
    { // doesn't seem to start from first line
      tokenizer = new StringTokenizer(line, delimiter);
      node++;
      System.out.println("Input Line: \t" + line);
      System.out.print("Tokens: \t");
      
      adjMatrix = new int [node][node];// to get the number of rows and columns - but I know this is wrong...
      
      while (tokenizer.hasMoreTokens())
      {// process tokens in line
        token = tokenizer.nextToken();
        System.out.print(token);
        
       
       
        for(int x = 0; x < token.length(); ++x)
            for(int j = 0; j < token.length(); ++j)
            {
            	adjMatrix[x][j] = Integer.parseInt(tokenizer.nextToken());
            }
            
      }// close inner while
       
      System.out.println();
  
      line = input.readLine(); // next line
    }// close outer while

//below are different tests
//node would be the number of rows I'm still working on how to get the columns I guess that would be counting the tokens after they are being split
//seeing if the number got into the adjMatrix 
//seeing if I could print out the adjMatrix
    
    System.out.println(node);
    System.out.println(adjMatrix.length);
    
    for(int x = 0; x < token.length(); ++x)
        for(int j = 0; j < token.length(); ++j)
        {
        	System.out.println(adjMatrix[x][j]);
        }
    
  }
}

this is the output without the two for loops putting the tokens into the adjMatrix

Input Line: 	0 1 0 0 1 1 0 0
Tokens: 	0010
Input Line: 	1 0 0 0 0 1 1 0
Tokens: 	1001
Input Line: 	0 0 0 1 0 0 1 0
Tokens: 	0001
Input Line: 	0 0 1 0 0 0 0 1
Tokens: 	0100
Input Line: 	1 0 0 0 0 1 0 0
Tokens: 	1000
Input Line: 	1 1 0 0 1 0 0 0
Tokens: 	1010
Input Line: 	0 1 1 0 0 0 0 1
Tokens: 	0100
Input Line: 	0 0 0 1 0 0 1 0
Tokens: 	0001
8
8
0

output with the for loops commented out

Input Line: 	0 1 0 0 1 1 0 0
Tokens: 	01001100
Input Line: 	1 0 0 0 0 1 1 0
Tokens: 	10000110
Input Line: 	0 0 0 1 0 0 1 0
Tokens: 	00010010
Input Line: 	0 0 1 0 0 0 0 1
Tokens: 	00100001
Input Line: 	1 0 0 0 0 1 0 0
Tokens: 	10000100
Input Line: 	1 1 0 0 1 0 0 0
Tokens: 	11001000
Input Line: 	0 1 1 0 0 0 0 1
Tokens: 	01100001
Input Line: 	0 0 0 1 0 0 1 0
Tokens: 	00010010
8
8
0

[Jesper de Jong]

I think you can make this a lot simpler by not using StringTokenizer, but by just using line.split("\\s+") to split the values on a line.

[Carey Brown]

Lines 36-40 attempt to get the next x*j tokens when you are already pulling out the next token on line 31. You might want to make 36-40 your main loop and do away with the while() loop.

[Knute Snortum]

Your problem is in this line:

adjMatrix[x][j] = Integer.parseInt(tokenizer.nextToken());

You've already set token = tokenizer.nextToken();. The .nextToken() method moves the pointer. So what should the above line be?

[mayumi yamada]

So SORRY for the extremely late replies...I had a death in the family and didn't take it very well. But back to normal now. Thank you so much for the replies and suggestions!

@Jesper de Jong: how would I go about doing a split() so it can be in the adjMatrix

@Carey Brown: thanks I will try that

@Knute Snortum: ah, thank you for pointing that out! That should be just

adjMatrix[x][j] = Integer.parseInt(token);

I'm also looking for a split() since Jesper suggested that it would be better. I will update my progress

[mayumi yamada]

Okay, I fixed that. With something else. NOW, I am trying to save the first encounters of DFS into an array so it can be printed for later.
By first encounters : I mean what is first pushed on the stack or visited first.
Here is my now code.

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.*;

public class DFS {

private Stack<Integer> stack;

String line;
int row = 0;
static int size = 0;

public DFS(){
	
	stack = new Stack<Integer>();
	
}
	
public void dfs(int adjMatrix[][], int vert)
{
    int number_of_nodes = adjMatrix[vert].length - 1;

    int visited[] = new int[number_of_nodes + 1];	
    int element = vert;		
    int i = vert;		
    System.out.print(element + "\t");		
    visited[vert] = 1;		
    stack.push(vert);

    while (!stack.isEmpty())
    {
        element = stack.peek();
        i = element;	
    while (i <= number_of_nodes)
    {
    	
 	        if (adjMatrix[element][i] == 1 && visited[i] == 0)
        {
               
 	        	stack.push(i);
 	        	
                visited[i] = 1;
                element = i;
                i = 1;
                
                System.out.print(element + "\t");
                
            continue;
            }
            i++;
    }
        stack.pop();
        
   	    
    	
     }
}


public static int[][] create2DIntMatrixFromFile(String filename) throws Exception {
    int[][] matrix = null;

    BufferedReader buffer = new BufferedReader(new FileReader(filename));

    String line;
    int row = 0;
    int size = 0;

    while ((line = buffer.readLine()) != null) {
        String[] vals = line.trim().split(" ");

        // Lazy instantiation.
        if (matrix == null) {
            size = vals.length;
            matrix = new int[size][size];
        }

        for (int col = 0; col < size; col++) {
            matrix[row][col] = Integer.parseInt(vals[col]);
        }

        row++;
    }

    return matrix;
}

public static void main(String[] args)
{
	
	
	 int[][] matrix = null;

     try {
         matrix = create2DIntMatrixFromFile("sample.txt");
     } catch (Exception e) {
         e.printStackTrace();
     }

        System.out.println("The DFS Traversal for the graph is given by ");
        DFS dfs = new DFS();
        dfs.dfs(matrix, size);					
   }	
}

This is the output

The DFS Traversal for the graph is given by 
0	1	5	4	6	2	3	7

** edit.
Just found out that my traversal is WRONG so I am now trying to figure out what's going on here

[Campbell Ritchie]

So what is the algorithm for the traversal? You should turn your computer off and write the algorithm on a piece of paper. Then you can turn it into code. You will probably have to delete all the old code if it is not working correctly.