Question

1. Modify the HighArray class to implement the method specified below, which reads integer data from a file to fill the array. The first integer read from the file should indicate the number of integers contained in the file which can be read into the array.

/**
* Read integers into array from named file. First element in
* file is a count of number of integers contained in the file.
*
* @param fileName   name of file containing integer data
*/
void readIntFile(String fileName)

Note: Use the void insert(int value) method defined in the class to add each integer to the array as it is loaded from the file.

Here is a sample code to read data from file

import java.io.File;

import java.io.FileNotFoundException;

import java.util.Scanner;

public class FileReaderSample {

    public static void main(String[] args) throws FileNotFoundException {

        Scanner in = new Scanner(System.in);

        System.out.println("Please enter file name");

      String s = in.nextLine();

        Scanner input = new Scanner(new File(s));

        int[] arr = new int[100];

        int i = 0;

        while (input.hasNextInt()) {

            int next = input.nextInt();

            arr[i] = next;

            i++;

        }// end while

        int nElems = i;

// Print the array contents

       System.out.println("Array Contents");

        for (i = 0; i < nElems; i++) {

            System.out.println(i + "\t" + arr[i]);

        }// end for

    }// end main

Answer 1

Short Summary:

Implemented the program as per requirement

Attached source code and sample output

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Source Code:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

/**This class reads integer data from a file to fill the array**/
public class HighArray {

   /**
   * Read integers into array from named file. First element in
   * file is a count of number of integers contained in the file.
   *
   * @param fileName name of file containing integer data
   */
   void readIntFile(String fileName)
   {
       Scanner input =null;
       try {
           //Create file with given File name
           input = new Scanner(new File(fileName));
       } catch (FileNotFoundException e) {
           e.printStackTrace();
       }

       int i = 0;
       int[] arr = null ;
       int arraySize=0;

       while (input.hasNextInt()) {
           //First element in the array is size of the array, as it contains no of elements
           if(i==0)
           {
               arraySize=input.nextInt();
               arr = new int[arraySize];
           }
           else
           {
               //Load array from second element
               int next = input.nextInt();
               //Start from zero'th index
               arr[i-1] = next;
           }
           i++;

       }// end while

       // Print the array contents

       System.out.println("*******Array Contents******");

       for (i = 0; i < arraySize; i++) {

           System.out.println(i + "\t" + arr[i]);

       }// end for
       input.close();
   }// end Method

   //Main method to test the above method
   public static void main(String[] args)
   {
       //Create object for HighArray
       HighArray obj=new HighArray();
       Scanner in=new Scanner(System.in);
       //Get file name input from user
       System.out.print("Please enter the file name: ");
       obj.readIntFile(in.nextLine());
       in.close();
   }
}

Code Screenshot:

Output:

InputFile.txt

Output:

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