Reading Lines with BufferedReader

Question

I am trying to read information from a file to interpret it. I want to read every line input. I just recently learned about bufferedreader. However, the problem with my code is that it skips every other line.

For example, when I put in 8 lines of data, it only prints 4 of them. The even ones.

Here is the code:

import java.io.*;
import java.util.Scanner;

public class ExamAnalysis
{
  public static void main(String[] args) throws FileNotFoundException, IOException
  {

    int numOfQ = 10;

    System.out.println();
    System.out.println("Welcome to Exam Analysis.  Let’s begin ...");
    System.out.println();
    System.out.println();

    System.out.println("Please type the correct answers to the exam     questions,");
    System.out.print("one right after the other: ");
    Scanner scan = new Scanner(System.in);
    String answers = scan.nextLine();

    System.out.println("What is the name of the file containing each student's");
    System.out.print("responses to the " + numOfQ + " questions? ");
    String f = scan.nextLine();
    System.out.println();

    BufferedReader in = new BufferedReader(new FileReader(new File(f)));
    int numOfStudent= 0;

    while ( in.readLine() != null )
    {
      numOfStudent++;
      System.out.println("Student #" + numOfStudent+ "\'s responses: " + in.readLine());
    }
    System.out.println("We have reached “end of file!”");             
    System.out.println();
    System.out.println("Thank you for the data on " + numOfStudent+ " students. Here is the analysis:");
   }
 }
 }

I know this may be a bit of a bad writing style. I am just really new to coding. So if there is any way you can help me fix the style of the code and methods, I would be really thrilled.

The point of the program is to compare answers with the correct answer. Thus I also have another question:

How can I compare strings with the Buffered Reader? Like how can I compare ABCCED with ABBBDE to see that the first two match but the rest don't.

Thank you

Answer 1

the problem with my code is that it skips every other line

Your EOF check thows a line away on each iteration

while ( in.readLine() != null ) // read (first) line and ignore it
{
  numOfStudent++;
  System.out.println("Student #" + numOfStudent+ "\'s responses: " + 
    in.readLine());   // read (second) next line and print it
}

to read all line do the following:

String line = null;
while ( null != (line = in.readLine())) // read line and save it, also check for EOF
{
  numOfStudent++;
  System.out.println("Student #" + numOfStudent+ "\'s responses: " + 
    line);   // print it
}

To compare Strings you need to use the String#compareTo(String other) method. Two Strings are equal if the return value is 0.

Answer 2

You don't compare Strings with readLine(). You compare them with String.equals().

Your reading code skips every odd line for the reason mentioned in the duplicate.