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Thread: Remove duplicates from ArrayList without API and print onto cvs file

  1. #1
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    Default Remove duplicates from ArrayList without API and print onto cvs file

    Hi, I'm trying to remove duplicates from an ArrayList made from tokens (from cvs file) using Scanner method. The file output from my code does not remove duplicates!

    import java.io.*;
    import java.util.*;
     
    public class removeDuplicates {
     
        public static void main (String[] args) throws IOException {
     
            String line = "";
            StringBuilder addToFile  = new StringBuilder();
     
            try{
                Scanner myFile = new Scanner(new File("data.csv"));
                File output = new File("correctedData.cvs");
     
                while (file.hasNext()){
                    line = file.nextLine();
                    String[] tokens = line.split(",");
                    List<String> List = new ArrayList<>();
                    List.add(tokens[3]);
     
                    List<String> newList = new ArrayList<>();
                    for (String x : List){
                        if (!newList.contains(x)) {
                            newList.add(x);
                        }
                  }
                    addToFile.append("\n").append(newList);
     
     
                }
                file.close();
                PrintWriter fileSave = new PrintWriter(output);
                fileSave.println(addToFile);
                fileSave.close();
     
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
     
     
    }

    MY OUTPUT:

    [mumbai]
    [london]
    [paris]
    [london]

    Duplicates not removed...
    Last edited by nosleep123; October 11th, 2020 at 12:25 AM.

  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Remove duplicates from ArrayList without API and print onto cvs file

    Can you describe the steps the code needs to take to remove the duplicates? You need to have that algorithm before trying to write the code.

    Note: Having comments in the code can make it easier for anyone reading the code to understand what the code is trying to do. Please add comments to the code that describe what it is doing and why it is doing it.
    For example why does it create a new list in every iteration of the loop?
    If you don't understand my answer, don't ignore it, ask a question.

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