Question

composed the following java code to read a string from a text file but receiving compiling errors. The text file is MyNumData.txt. Included the original java script that generated the output file.

Shown also in the required output results after running the java program. I can't seem to search for the string and output the results. Any assistance will be greatly appreciated.

import java.io.BufferedReader;

import java.io.FileReader;

import java.util.ArrayList;

public class Main {

  public static void main(String[] args) {

    System.out.print("Enter the name of the input file to search:");

    final String file = "MyNumData.txt";

    fname = scan.nextLine();

    String line = null;

    ArrayList<String> fileContents = new ArrayList<>();

    System.out.print("Please enter the string to search:");

try {

      FileReader fReader = new FileReader(file);

      BufferedReader fileBuff = new BufferedReader(fReader);

      while ((line = fileBuff.readLine()) != null) {

        fileContents.add(line);

      }

      System.out.println ("The following lines were found:", ++line);

      fileBuff.close();

    } catch (Exception e) {

      System.out.println(e.getMessage());

    }

    }

}

java code that generates the ouput file:

import java.io.*;

import java.util.Scanner;

public class CodingChallenge5CRM {

  public static void main(String[] args){

    Scanner sc = new Scanner(System.in);

    System.out.println("Welcome to the Prime, Perfect Square, and Perfect Number Tester ");

    System.out.print("Please enter the name of the output file to save your data:");

    String name = sc.nextLine();

    PrintWriter pw = null;

    try {

      FileOutputStream fout = new FileOutputStream(name);

      pw = new PrintWriter(fout);

    }

    catch (Exception e){

      e.printStackTrace();

    }

    System.out.print("Enter a start number:");

    int a = Integer.parseInt(sc.nextLine());

    System.out.print("Enter a stop number:");

    int b = Integer.parseInt(sc.nextLine());

    

    for (int i = a; i<=b; i++){

      int ps = 0;

      for (int k = 0; k<a; k++){

        if (k*k == i){

         ps = 1;

         System.out.println("The number " + i+ " is: Perfect Square");

         pw.println("The number " + i+ " is: Perfect Square");

        }

      }

      if (ps == 1)

       continue;

      int sum = 0;

      for (int j = 2; j<i; j++){

        if (i % j == 0)

         sum = sum + j;

      }

      if (sum == 0){

        System.out.println("The number " + i+ " is: Prime");

        pw.println("The number " + i+ " is: Prime");

      }

      else if (sum + 1 == i){

        System.out.println("The number " + i+ " is: Perfect");

        pw.println("The number " + i+ " is: Perfect");

      }

      else if (sum + 1 > i){

        System.out.println("The number " + i+ " is: Imperfect Abundant");

        pw.println("The number " + i+ " is: Imperfect Abundant");

      }

      else{

        System.out.println("The number " + i+ " is: Imperfect Deficient");

        pw.println("The number " + i+ " is: Imperfect Deficient");

      }

    }   

       

  }

Output needs to look like this:

Welcome to the Prime, Perfect Square, and Perfect Number Tester

Enter the name of the output file: MyNumData.txt

Enter a start number: 20

Enter a stop number : 30

The number 20 is: Imperfect Abundant

The number 21 is: Imperfect Deficient

The number 22 is: Imperfect Deficient

The number 23 is: Prime

The number 24 is: Imperfect Abundant

The number 25 is: Perfect Square

The number 26 is: Imperfect Deficient

The number 27 is: Imperfect Deficient

The number 28 is: Perfect

The number 29 is: Prime

The number 30 is: Imperfect Abundant

Enter the name of the input file to search: MyNumData.txt

Enter the string to search: prim

The following lines were found:

The number 23 is: Prime

The number 29 is: Prime

Answer 1

Below is the updated code as per the requirements. Changes are highlighted in bold:

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String line, fname;

        System.out.print("Enter the name of the input file to search: ");
        fname = scan.nextLine(); // read file name

        ArrayList<String> fileContents = new ArrayList<>();
        System.out.print("Please enter the string to search: ");
        String search = scan.nextLine(); // read string to search

        try {
            FileReader fReader = new FileReader(fname);
            BufferedReader fileBuff = new BufferedReader(fReader);
            while ((line = fileBuff.readLine()) != null) {
                // add to file contents if search string exists in line
                if (line.toLowerCase().contains(search.toLowerCase())) {
                    fileContents.add(line);
                }
            }

            System.out.println("The following lines were found:");
            for (String l : fileContents) {
                System.out.println(l);
            }

            fileBuff.close();

        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }
}

Also, I found one issue in your CodingChallenge5CRM code, you are not closing the PrintWriter instance pw. Please close this using below statement:

pw.close();

Below is the sample output showing execution after the fix:

Enter the name of the input file to search: MyNumData.txt Please enter the string to search: prim The following lines were found The number 23 is Prime The number 29 is: Prime BUILD SUCCESSFUL (total time: 4 seconds)

This completes the requirement. Let me know if you have any queries.

Thanks!