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up vote 2 down vote favorite

Edit Adapted code since then. Would still like to eliminate repeated bits of code... Cannot think how. 

public static void readFile(String fileName) throws IOException, FileNotFoundException{

    double fileX;
    double fileY;
    double fileZ;

    // Reference the file using the the BufferedReader object
    BufferedReader input = new BufferedReader(new FileReader(fileName));    

    //scanner to scan through file 
    Scanner token = new Scanner(input);

    /*
     * skipToDouble() method makes it possible to search my file for double values
     */

    // initialize x, y and z to place inside vector A 
    fileX= skipToDouble(token);
    fileY= skipToDouble(token);
    fileZ= skipToDouble(token);

    vecA = new Vector3D(fileX,fileY,fileZ);

    // initialize x, y and z to place inside vector B 
    fileX= skipToDouble(token);
    fileY= skipToDouble(token);
    fileZ= skipToDouble(token);

    vecB = new Vector3D(fileX, fileY, fileZ);

    // initialize x, y and z to place inside vector C (dummy vector really)
    fileX= skipToDouble(token);
    fileY= skipToDouble(token);
    fileZ= skipToDouble(token);

    //initialize vecC using double values from third line of file
    vecC = new Vector3D(fileX, fileY, fileZ);   

    //close file 
    input.close();
}
//keeps looking until double is found
private static double skipToDouble(Scanner scanner) {
    while (scanner.hasNext() && !scanner.hasNextDouble()) {
        scanner.next();
    }
    return scanner.hasNextDouble() ? scanner.nextDouble() : Double.NaN;
}

EDIT: Trying the suggestion I am not getting a NullInputException and cannot see why:

// Reference the file using the the BufferedReader object
    BufferedReader input = new BufferedReader(new FileReader(fileName));    

    //scanner to scan through file 
    Scanner tokens = new Scanner(input);

    for(int i=0; i<3; i++){

        System.out.print("i = " + i);

        for(int j=0; j<3; j++){
            System.out.print("j = " + j);

            file[j]=skipToDouble(tokens);
        }
        vec[i]= new Vector3D(file[0], file[1], file[2]);
    }


    //close file 
    input.close();
share|improve this question
two methods readNextDouble and readNextVector using these two methods. – Sulthan Oct 8 '12 at 8:44

3 Answers

up vote 1 down vote accepted

You don't need to track the double in fileX, fileY, and fileZ. Instead of this:

fileX= skipToDouble(token);
fileY= skipToDouble(token);
fileZ= skipToDouble(token);

vecA = new Vector3D(fileX,fileY,fileZ);

You could consider this:

vecA = new Vector3D(
        skipToDouble(token),
        skipToDouble(token),
        skipToDouble(token)
);
share|improve this answer
Yep that worked nicely. Thanks. – Magpie Oct 6 '12 at 21:26
up vote 2 down vote

You could factor out the repetitive code into a separate method, and then reduce the repetition further there.

Maybe like this:

private static Vector3D readNextVector3D(Scanner token)
{
    while ( !token.hasNextDouble() )
    {
        token.next();
    }

    String[] nextLine = token.nextLine().split(" ");
    assert(nextLine.length == 3);
    return new Vector3D( Double.parseDouble(nextLine[0]),
                         Double.parseDouble(nextLine[1]),
                         Double.parseDouble(nextLine[2]) );
}
share|improve this answer
thanks for the answer. I had done something a bit similar to that which I have reposted. I still would like to cut the x y z repeated bits though – Magpie Oct 6 '12 at 2:47
up vote 1 down vote

Instead of using fileX, fileY, fileZ you could use double[3] to represent them. Same with VecA, VecB, VecC. Then you could write something like:

for(i=0; i<3; i++)
{
   for(j=0;j<3;j++)
   {
      file[j]=skipToDouble(token);
   }
   vec[i]=new Vector3D(file[0], file[1], file[2]);
}
share|improve this answer
ok I will try this. Thanks. – Magpie Oct 6 '12 at 13:24
I am getting a null input exception // Reference the file using the the BufferedReader object BufferedReader input = new BufferedReader(new FileReader(fileName)); //scanner to scan through file Scanner tokens = new Scanner(input); for(int i=0; i<3; i++){ System.out.print("i = " + i); for(int j=0; j<3; j++){ System.out.print("j = " + j); file[j]=skipToDouble(tokens); } vec[i]= new Vector3D(file[0], file[1], file[2]); } //close file input.close(); – Magpie Oct 6 '12 at 20:46

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