Java - reading from file returns null

Question

This question has been asked a few times before on stack overflow and I wanted to stress that I have looked into the solutions and yet to overcome my problem.

I have an program that should read data from a file and store it within the array. I am currently running some tests to ensure the data is being read correctly and one of these are a simple output to the terminal. Each time I wanted to print out the data, I keep getting "null".

Looking into the problem I set each of the array elements to "". So I initialised them. Now the terminal just displays a blank line. It seems the content from the file isn't being read to the array?

the file being read content:

Q1: (A + B)*(A+B) \n 1. A*A + B*B \n 2. A*A +A*B + B*B \n 3. A*A +2*A*B + B*B \n
Q2: (A + B)*(A - B) \n 1. A*A + 2*B*B \n 2. A*A - B*B \n 3. A*A -2*A*B + B*B \n
Q3: sin(x)*sin(x) + cos(x)*cos(x) \n 1. 1 \n 2. 2 \n 3. 3 \n

How I am reading it(code snippet is in a method):

try 
{
    int i =0;
    String [] line = new String [10];
    for (i=0;i<=9;i++)
    {
        line[i] = "";
    }
    Scanner scanner = new Scanner(new File("questions.txt"));
    scanner.useDelimiter("Q");
    i=0;
    while (scanner.hasNext()) 
    {
        line[i] = scanner.next();
        i++;
        System.out.println("" + line[i]);
    }
}
catch (FileNotFoundException exp)
{
    exp.printStackTrace();
}

You have an i++; before the sysOut. I think that's why you're not seeing the contents read. Try switching the two statements — Vineet
– Vineet, Commented Feb 22, 2015 at 12:14
@VineetRamachandran Thanks. Stupid mistake I missed. Would you mind making your comment a answer so I can give the green tick? — lecardo
– lecardo, Commented Feb 22, 2015 at 12:16

Vineet · Accepted Answer · 2015-02-22 12:50:39Z

1

You have an i++; before the sysOut. I think that's why you're not seeing the contents read. Try switching the two statements.

answered Feb 22, 2015 at 12:50

Vineet

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Comments

Neeraj Jain · Accepted Answer · 2015-02-22 13:07:55Z

0

Here is your problem

  line[i] = scanner.next();
  i++; // Incrementing the Index before printing
  System.out.println("" + line[i]);

Try this

  line[i] = scanner.next();
  System.out.println("" + line[i++]);

answered Feb 22, 2015 at 13:07

Neeraj Jain

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