Thread: Having trouble splitting a text file into multiple arrays.

Hey all, working on trying to read in a text file so that I can split it into multiple arrays. Text file looks like this

 
Amy Adams
10111
97 86 78 95
Ben Barr
20222
89 81 73 87
Carla Carr
30333
79 71 63 77
Don Davis
40444
69 62 58 67
Edna Eaton
50555
63 51 62 48

The name, the student id, and a set of their 4 grades must be split into seperate arrays so that they can be used later to calculate avg's and so on. I'm having trouble getting them to go into different arrays.

This is what I have so far.

import java.io.*;
 
public class Program2 {
 
    public static void main(String[] args) throws IOException {
 
        File dataFile = new File("G:\\COSC 1337\\Handouts  6-14\\Student Data.txt");
        BufferedReader br = new BufferedReader(new FileReader(dataFile));
        String str;
        String[] names = new String[5];
        int[] grades = new int[20];
        String[] studentID = new String[20];
 
        for (int i = 0; i < 5; i++) {
            str = br.readLine();
            names[i] = str;
            str = br.readLine();
            studentID[i] = str;
            str = br.readLine();
            grades[i] = Integer.parseInt(str);
        }

I keep getting a numberFormatexception, I assume from trying to parse the string for grades... but I'm unsure how to go about getting all the grades into an array, if everything else is only strings.

It's not very clear in the assignment but it's listed below. I assume I have to save each set of 4 grades into it's own little box, and calculate an avg from that...but it seems very difficult. We've only learned about one dimensional arrays so far.

Create ONE 1-D Array to hold a set of four test scores for five students. 
 
Create parallel arrays to hold student names, student id, average 
score, and a letter grade based on standard grade scale.
 
Populate the arrays from the file Student Data.txt
 
  Write a program to do the following tasks:
 
    1. Calculate average score for each student.
    2. Assign letter grade for each student.
    3. Display name, id, scores, average, and grade for each student. 
    4. calculate the class average score and display.

You can use the split method on the String containing the numbers in order to get an array of all the numbers. Also, you may want to store each array of numbers in a List as an alternative.

Originally Posted by Norm

Do you have a technique for getting the each of the four grades from the line that they are on?

I was going to use what he stated above. I've used the split method, but was going to create a integer array and just hold all the grades in each of their elements. Then when it comes to calculating avg, I was going to just take array[0] to [3] on each person and add those and divide by 4. I think. easier said then done.

I'm having trouble breaking the 4 sets of numbers apart so that I can parse them into ints.

 
import java.io.*;
 
public class Program2 {
 
    public static void main(String[] args) throws IOException {
 
        File dataFile = new File("G:\\COSC 1337\\Handouts  6-14\\Student Data.txt");
        BufferedReader br = new BufferedReader(new FileReader(dataFile));
        String str;
        String[] placeHolder = new String[5];
        String[] names = new String[5];
        int[] grades = new int[20];
        String[] studentID = new String[20];
 
 
        for (int i = 0; i < 5; i++) {
            str = br.readLine(); //read first line
 
            names[i] = str; // put data into name array
 
            str = br.readLine(); // read second line
 
            studentID[i] = str; // put data into studentID array
 
            str = br.readLine(); //read third line
 
           str.split(" ");
           Integer.parseInt(str);
 
 
 
 
 
           }
 
    }
}

This is what I came up with... but it's trying to parse a set of 4 numbers still. How can I get it to parse each individual number if it's reading in the whole line at once?

 
import java.io.*;
 
public class Program2 {
 
    public static void main(String[] args) throws IOException {
 
        File dataFile = new File("G:\\COSC 1337\\Handouts  6-14\\Student Data.txt");
        BufferedReader br = new BufferedReader(new FileReader(dataFile));
        String str = new String();
 
        String[] placeHolder = new String[5];
        String[] names = new String[5];
        int[] grades = new int[20];
        String[] studentID = new String[20];
        String[] setsOfGrades = new String[5];
 
 
        for (int i = 0; i < 5; i++) {
            str = br.readLine(); //read first line
 
            names[i] = str; // put data into name array
 
            str = br.readLine(); // read second line
 
            studentID[i] = str; // put data into studentID array
 
            str = br.readLine(); //read third line
 
            placeHolder = str.split(" ");
 
            for (int j = 0; j < placeHolder.length; j++) {
                grades[i] = Integer.parseInt(placeHolder[j]);
            }
 
 
        }
for(int i=0; i<grades.length; i++)
{
    System.out.println(grades[i]);
}
    }
}

OUTPUT

95
87
77
67
48
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

It's just picking random numbers to save and I'm not sure why.

I printed out the String str and it of course prints the first four correct grades that should be read in. It prints out "97 86 78 95", which it should. Everything seems to go wrong when I do the split. The reason I put the array placeHolder to have and index of 5 is because I thought it was saving each SET of 4 grades into one element...hence I put an index of 5. What I can't figure out... is the splitting of the group of 4 numbers... that's what has me confused. I printed out the placeHolder array using your toString method and it just prints out

 
[Ljava.lang.String;@19821f
[Ljava.lang.String;@addbf1
[Ljava.lang.String;@42e816
[Ljava.lang.String;@9304b1
[Ljava.lang.String;@190d11

 
import java.io.*;
 
public class Program2 {
 
    public static void main(String[] args) throws IOException {
 
        File dataFile = new File("G:\\COSC 1337\\Handouts  6-14\\Student Data.txt");
        BufferedReader br = new BufferedReader(new FileReader(dataFile));
        String str = new String();
 
        String[] placeHolder = new String[21];
        String[] names = new String[5];
        int[] grades = new int[5];
        String[] studentID = new String[20];
        String[] setsOfGrades = new String[5];
 
 
        for (int i = 0; i < 5; i++) {
            str = br.readLine(); //read first line
 
            names[i] = str; // put data into name array
 
            str = br.readLine(); // read second line
 
            studentID[i] = str; // put data into studentID array
 
            str = br.readLine(); //read third line
 
            placeHolder = str.split(" ");
            System.out.println(placeHolder.toString());
 
 
 
 
            for (int j = 0; j < placeHolder.length; j++) {
                grades[i] = Integer.parseInt(placeHolder[j]);
            }
 
 
        }
for(int i=0; i<grades.length; i++)
{
   //System.out.println(grades[i]);
}
    }
}

Yes, I have done that...but it keeps telling me it cannot find the symbol with red lining under Arrays. (I'm using Netbeans btw.) Sorry for being confusing. Trying my best to figure out these errors/logic.