The document is a Java program that simulates the attributes of hobbits by generating random height and weight values, storing them in a two-dimensional array. It includes methods to populate the array, write the data to a CSV file, and read the CSV back to display the data along with the averages of each attribute. The program accepts five hobbits, with output confirming successful reading and writing of data.

1. //import statemnts for Random, Scanner and IO
import java.util.Random;
import java.util.Scanner;
import java.io.*;
public class Hobbits
{
public static void main(String[] args) throws IOException
{
final int NUM_HOBBITS = 5;
final int NUM_COLUMNS = 2;
String fileName = "hobbits.csv";
//call populateHobbits( ) to create the two dimensional array
double[][] hobbits = populateHobbits(NUM_HOBBITS, NUM_COLUMNS);
//display the number of hobbits
System.out.println(hobbits.length + " hobbits accepted Gandalf's invitation to lunchn");
//calculate the means of the columns
double[] hobbitMeans = getColMeans(hobbits);
//write hobbits array to file
writeHobbits(hobbits, fileName);
//read and display the file that has been read
readHobbitses(fileName);
//call displayColMeans to display hobbit means
displayColMeans(hobbitMeans);
}
//method to populate hobbits array with random double values
public static double[][] populateHobbits(int numHobbits, int numCols)
{
final double HT_MULTIPLIER = 10.0; //multiplier for the hobbit height
final double WT_MULTIPLIER = 250.0; //multiplier for the hobbit weight
//instantiate Random object
Random rand = new Random();
//declare two dim array with numHobbits rows numCols columns
double[][] hobbitArray = new double[numHobbits][numCols];

2. //assign random double values to all elements
for (int i = 0; i < numHobbits; i++) //outer loop is for rows
{
for (int j = 0; j < numCols; j++) //inner loop is for columns
{
//get a random double value in range [0.2, 0.4]
double randDouble = getRandDouble(rand);
//assign this double to the current array element
hobbitArray[i][j] = randDouble;
//determine which multiplier to use
if (j == 0) //this is column for height
hobbitArray[i][j] *= HI_MULTIPLIER;
else //this is column for weight
hobbitArray[i][j] *= WT_MULTIPLIER;
}
}
return hobbitArray; //return the two dimensional array
}
//method to write hobbits array to file
public static void writeHobbits(double[][] ar, String fileName) throws IOException
{
//open the file to write
PrintWriter outFile = new PrintWriter(fileName);
//print columen heading of the array of stats
outFile.println("HEIGHT,WEIGHT");
for (int i = 0; i < ar.length; i++)
{
for (int j = 0; j < ar[i].length; j++)
{
outFile.print(ar[i][j]);
//if at end of a row, add newline char
if (j == ar[i].length - 1)
outFile.print("n");
else //add the "," delimiter
outFile.print(",");
} //end of inner loop
} //end of outer loop
outFile.close(); //close outfile

3. System.out.println("The file was successfully writtenn");
} //end of method
//method to read the hobbits file
public static void readHobbitses(String fileName) throws IOException {
//open the file to read
File dataFile = new File(fileName);
Scanner inFile = new Scanner(dataFile);
//variable to contain the substrings of one line of file
String[] oneLine = new String[2];
int counter = 0; //keep track of line numbers
System.out.println("Data read from the " + fileName + " file:");
//read file, one line at a time
while (inFile.hasNext()) {
String dataLine = inFile.nextLine();
oneLine = dataLine.split(","); //split line with delimiter
if (counter > 0) //for second line and beyond, format doubles
{
System.out.printf("%.2ftt%.2fn", Double.parseDouble(oneLine[0]),
Double.parseDouble(oneLine[1]));
} else //if this first line, display the column heading
System.out.println(oneLine[0] + "t" + oneLine[1]);
if (inFile.hasNext())
counter++; //keep track of how many lines
} //end while loop read file
inFile.close(); //close the file
System.out.println("The file has now been successfully read.n");
} //end of method
//method to determine average values of columns two dim array
public static double[] getColMeans(double[][] ar) {
//local array to store means
//array is sized according to length second dimension of parameter
//first element is mean of first column
//second element is mean of second column, etc
double[] meanAr = new double[ar[0].length];

4. //nested for loop to iterate through elements in parameter
for (int i = 0; i < ar.length; i++) {
for (int j = 0; j < ar[i].length; j++) {
//sum the elements in the current column
meanAr[j] += ar[i][j];
}
} //end of outer loop
//replace the sum with the average; i.e. divide by number of rows
for (int i = 0; i < meanAr.length; i++)
meanAr[i] /= ar.length;
Lab16 Sample output