Reputation: 13

Counting values in a column of a .csv file Java

I'm tasked, by my professor, to write a program to read a .csv file (778 rows (including header row), 8 columns). I need to: 1. Write a method to receive the name of the file as its argument and then print the number of lines in the file.

public void printNumberOfLinesInFile(String fileName)

Write a method to receive the name of the file as its argument and then print the number of private and non-private colleges.

public void printNumberOfPrivateNonPrivateCollegesInFile(String fileName)

Write a method to receive the name of the file as its argument and then print the private college name with largest out of state tuition.

public void printMostExpensivePrivateCollegeInFile(String fileName)

Write a method to receive the name of the file as its argument and then print the non-private college with largest out of state tuition.

public void printMostExpensiveNonPrivateCollegeInFile(String fileName)

Write a method to receive the name of the file as its argument and then print the number of applications and the number of applicants that are accepted for private and non-private colleges.

public void printNumberOfApplications(String fileName)

Write a method to receive the name of the file as its argument and then print following information for private and non-private colleges.

Average of expenses for books. Average of expenses for room. Average of personal expenses.

public void printAverageOfExpenses(String fileName)

Disclaimer: I do not want anyone to do my homework for me. I need to learn so I can apply my knowledge when I graduate and enter industry. I'm simply asking for a hint or a better way at writing the code.

My code thus far:

    public class Week14 
    {
public String data;



public void printNumberOfLinesInFile(String inFile) throws IOException
{
    int collegeCount = 0;
    FileReader fileRead = new FileReader(inFile);
    BufferedReader bufferRead = new BufferedReader(fileRead);
    while(true)
    {
        String line = bufferRead.readLine();
        if(line == null)
        {
            break;

        }
        collegeCount++;
        //System.out.println(line);
    }
    System.out.println(collegeCount-1 + " Colleges total.");
}
public void printNumberOfPrivateNonPrivateCollegesInFile(String inFile) throws IOException
{
    int privateCount = 0;
    int nonprivateCount = 0;
    int count = 0;
    FileReader fileRead = new FileReader(inFile);
    BufferedReader bufferRead = new BufferedReader(fileRead);
    while((data = bufferRead.readLine())!= null)
    {
        String line = bufferRead.readLine();
        String [] lineItems = line.split(",");
        for(int i = 0; i < line.length(); i++)
        {
            if(lineItems[i].equals("Yes"))
            {
                privateCount++;
            }
        }

        break;
    }
    System.out.println(privateCount+" private Colleges.");
    System.out.println(nonprivateCount+ " non-private Colleges.");
}

public void printMostExpensivePrivateCollegeInFile(String inFile) throws FileNotFoundException, IOException
{
    int mostExpensive = 0;
    int currentExpensive = 0;
    FileReader fileRead = new FileReader(inFile);
    BufferedReader bufferRead = new BufferedReader(fileRead);
    while((data = bufferRead.readLine())!= null)
    {
        String line = bufferRead.readLine();
        if(line.equals("OutstateTuition"))
        {
            System.out.println(line);
        }
        else
        {
            System.out.println(line);
        }
    }



}

public void printMostExpensiveNonPrivateCollegeInFile(String fileName)
{

}

public void printNumberOfApplications(String fileName)
{

}

public void printAverageOfExpenses(String fileName)
{

}
public static void main(String[] args) throws FileNotFoundException, IOException 
{
    File inFile = new File("College.csv");
    FileReader fileReader = new FileReader(inFile);
    BufferedReader buffReader = new BufferedReader(fileReader);
    Week14 w1 = new Week14();
    //w1.printNumberOfLinesInFile("College.csv");
    w1.printNumberOfPrivateNonPrivateCollegesInFile("College.csv");
    //^^^The above line goes into an infinite loop^^^
    //w1.printMostExpensivePrivateCollegeInFile("College.csv");
}

}

The problem is, I'm stuck on trying to count the amount of private and nonprivate colleges. In my method, printNumberOfPrivateNonPrivateCollegesInFile (line 39), I'm running into an exception: java.lang.ArrayIndexOutOfBoundsException: 8

I've asked my professor how I can avoid this, I've looked online and the problem seems to lie with the iterator int 'i'. I'm trying to traverse the array, and 'i' is out of bounds. When I put a '1' in

    if(lineItems[i].equals("Yes"))

for my privateCount, there is an output of 67 from privateCount, (I think it is counting the individual characters for some reason).

My question, what would be the most effective way to traverse the entire .csv file, and to access individual columns so I can count them and output them?

Any help would be greatly appreciated.

edit:

I have changed the while loop:

        while(true)
        {
        String line = bufferRead.readLine();
        String [] lineItems = line.split(",");
        if(line == null)
        {
            break;
        }

        for (String lineItem : lineItems) {
            privateCount++;
        }

    }

Now I can traverse the entire .csv file, but I'm receiving a java.lang.NullPointerException when I try and count.

edit 2: I've redone my while loop again,

    while(true)
    {
        String line = bufferRead.readLine();
        String [] lineItems = line.split(",");

        for (String lineItem : lineItems) {
            if (lineItem.equals("Yes")) {
                privateCount++;
            }
        }
        System.out.println(privateCount);

    }

I'm now counting the right value for privateCount, but there's a NullPointerException at :

    String [] lineItems = line.split(",");

and the loop will not let me put my 'echo' outside of the while-loop without a 'break' statement.

Upvotes: 1

Counting values in a column of a .csv file Java

Answers (3)

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