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Thread: Help with parallel array

  1. #1
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    Default Help with parallel array

    /*
    Program created by: Craig Noguez
    	A program that creates a file containing a table showing the student ID numbers and averages of
    	all the students in a course in ascending order by ID number.
    */
     
    import java.io.*;
    import java.util.Scanner;
     
    public class assignment6
    {
    	public static void main(String[] args) throws IOException
    	{
    		Scanner keyboard = new Scanner(System.in);
    		String fileName = "";
    		String[] idnumbers;
    		String[] array;
    		String[] average;
    		int index = 0;
    		String[] test = new String[100];
     
    		System.out.println("Enter the name of the file you would like to read.");
    		fileName = keyboard.nextLine();
     
    		System.out.println();
     
    		idnumbers = getid(fileName);
    		average = getavg(fileName);			
    		selectionSort(idnumbers);
    		System.out.println("Enter the name of the file you would like to save the data to.");
    		fileName = keyboard.nextLine();
     
    		PrintWriter outputFile = new PrintWriter(fileName);
    		outputFile.printf(" IdNumber						Average\n");
    		for(index = 0; index < average.length; index++)
    			if(average[index] == null)
    				outputFile.close();
    			else
    				outputFile.printf("%5s %23s\n", idnumbers[index], average[index]);
    	}
     
    	/**
    		A method to get the id-number from a text file.
     
    		@param fileName  The file to get the id-numbers from
    		@return idnumbers  Returns the array with the idnumbers stored
    	*/
     
    	public static String[] getid(String fileName) throws IOException
    	{
    		File file = new File(fileName);
    		Scanner inputFile = new Scanner(file);
    		int index = 0;
    		int startid = 2;
    		String[] idnumbers = new String[100];
    		String[] WholeFile = new String[100];
     
    		while(inputFile.hasNext() && index < idnumbers.length)
    		{
    			WholeFile[index] = inputFile.nextLine();
    			index++;
    		}
     
    		for(index = 0; startid < WholeFile.length; index++)
    		{
    			idnumbers[index] = WholeFile[startid];
    			startid += 4;
    		}
    		return idnumbers;
    	}
     
    	/**
    		A method to get the averages from a text file.
     
    		@param fileName The file to get the averages from
    		@return average  Returns an array with the averages stored in it
    	*/
     
    	public static String[] getavg(String fileName) throws IOException
    	{
    		File file = new File(fileName);
    		Scanner inputFile = new Scanner(file);
    		int index = 0;
    		int startavg = 3;
    		String[] WholeFile = new String[100];
    		String[] average = new String[100];
     
    		while(inputFile.hasNext() && index < average.length)
    		{
    			WholeFile[index] = inputFile.nextLine();
    			index++;
    		}
     
    		for(index = 0; startavg < WholeFile.length; index++)
    		{
    			average[index] = WholeFile[startavg];
    			startavg += 4;
    		}
    		return average;
    	}
     
    	/**
    		A method that sorts the inputed string into alphabetical order.
     
    		@param array  The string to be sorted.
    	*/
    	public static void selectionSort(String[] array)
    	{
    		int startScan, index, minIndex;
    		String minValue;
     
    		for (startScan = 0; startScan < (array.length-1); startScan++)
    		{
    			minIndex = startScan;
    			minValue = array[startScan];
    			for(index = startScan + 1; index < array.length; index++)
    			{
    				if (array[index] == null)
    					break;
    				else if (array[index].compareTo(minValue) < 0)
    				{
    					minValue = array[index];
    					minIndex = index;
    				}
    			}
    			array[minIndex] = array[startScan];
    			array[startScan] = minValue;
    		}
    	}
    }
    I need my id number to get sorted along with the average but I have no idea how to do it and my teacher barely touched on parallel arrays help please thanks!


  2. #2
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    Default Re: Help with parallel array

    Parallel arrays are evil. What you should do instead is create a Student class that holds the ID and score of each Student. Then you can have a single array (or List) to hold all the Student objects.
    Improving the world one idiot at a time!

  3. #3
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    Default Re: Help with parallel array

    Ya see thats easy ive looked at it and it would make life so much simpler but my teacher is a nazi and she wont let us use it

  4. #4
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    Default Re: Help with parallel array

    If your instruction state that you must use parallel arrays then what you have to do is each time you swap/move values in one array make the same swap/move in the other array.
    Improving the world one idiot at a time!

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