CODEWITHSUNDEEP
java
ross.c
ross.c

Reputation: 143

removing duplicate integers from a file

Trying to write a program that prompts the user to enter a filename. It then should read in a sequence of integers from the input file, and print out the integers, removing repeated values that appear consecutively. e.g., if the input file contains 1 2 2 1 5 1 1 7 7 7 7 1 1 1 1 1 1 1 1 1, your program should print out 1 2 1 5 1 7 1.

My code 

import java.util.Scanner;
import java.io.*;



public class Duplicate {
  public static void main(String[] args) {
  Scanner keyboard = new Scanner(System.in);
  System.out.print("Enter a filename: ");
  String fileName = keyboard.nextLine();
  if (fileName.equals("")) {
     System.out.print("Error: User did not specify a file name.");
  } else {
     Scanner inputStream = null;

     try {
        inputStream = new Scanner(new File(fileName));
     } catch (FileNotFoundException e) {
        System.out.println("File couldn't be found");
        System.exit(0);
     }

     String[] address = new String[100];

     int i = 0;
     while (inputStream.hasNextLine()) {
        String email = inputStream.nextLine();
        // System.out.println(email);

        address[i] = email;
        System.out.println(address[i]);
        i++;


        }
      }
   }
}

The expected output is Enter a filename: [1, 2, 1, 5, 1, 7, 1] I get this output Enter a filename: 1 2 2 1 5 1 1 7 7 7 7 1 1 1 1 1 1 1 1 1

I'm not sure how to remove the duplicate values, Havn't learnt how to use set so trying to find a different way any help would be great :)

Upvotes: 0

Views: 312

Answers (2)

Eritrean
Eritrean

Reputation: 16498

public class Duplicate {
   public static void main(String[] args) {
   Scanner keyboard = new Scanner(System.in);
   System.out.print("Enter a filename: ");
   String fileName = keyboard.nextLine();
   if (fileName.equals("")) {
      System.out.print("Error: User did not specify a file name.");
   } 
   else {
     Scanner inputStream = null;
    try {
        inputStream = new Scanner(new File(fileName));
    } 
    catch (FileNotFoundException e) {
       System.out.println("File couldn't be found");
       System.exit(0);
    }

   String[] address = new String[100];
   int i = 0;
       while (inputStream.hasNextLine()) {
           String email = inputStream.nextLine();
           // System.out.println(email);
            address[i] = email.replace(" ", "")+" ";// add a space at the end of the line

          char ch1,ch2; //Variables to compare charachters
          String result ="";//Variable to store the final result
           for(int j=0; j<address[i].length()-1; j++){
               ch1=address[i].charAt(j); // get the first character
               ch2=address[i].charAt(j+1); // get the next character 
              if(ch1!=ch2) {// compare first and second, second and third ..., and so on; if not equal add to result            
              result = result + ch1;
              }
            }
          char [] res = result.toCharArray();
          System.out.println(Arrays.toString(res)); // Printing the result
          i++;
      }
    }
  }  
}

Upvotes: 1

Sanjeev
Sanjeev

Reputation: 9946

As you problem is not exactly removing duplicates for which you could have used Set, you want to remove consecutive duplicates only. So for that you have to keep track of current int and compare it against the next inline, if it matches skip it else add it to a list.

Following code shows how to do this. You can replace your while loop with this:

   List<Integer> uniques = new ArrayList<Integer>();


    while(inputStream.hasNextInt()) {
        int num = inputStream.nextInt();
        if(uniques.isEmpty()) {
            uniques.add(num);
        } else {
            if(num!=uniques.get(uniques.size()-1)) {
                uniques.add(num);
            }
        }
    }

    System.out.println(Arrays.toString(uniques.toArray()));

Hope this helps.

Upvotes: 0

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