問題描述

我應該讀入一個包含許多不同電子郵件地址的文件并使用數組將它們打印出來.問題是我需要消除重復的電子郵件.

I am supposed to read in a file containing many different email addresses and print them out using an array. The problem is I need to eliminate duplicate emails.

我能夠讓我的 try/catch 工作并打印出電子郵件地址.但是，我不確定如何刪除重復項.我還不了解哈希碼或如何使用 Set.任何幫助將不勝感激.

I was able to get my try / catch working and print out the email addresses. However, I am not sure how to go about removing the duplicates. I do not have an understanding of hashcode's or how to use a Set yet. Any assistance would be appreciated.

這是我目前所擁有的:

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

public class Duplicate {
   public static void main(String[] args) {

      Scanner keyboard = new Scanner(System.in);
      System.out.println("Enter file name: ");
      String fileName = keyboard.nextLine();
      if (fileName.equals("")) {
         System.out.println("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("Error: " + fileName + " does not exist.");
            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++;
         }
      }
   }
}

推薦答案

簡單的解決方案是使用java的Set，

The Simple solution is that use Set of java,

所以設置自動刪除重復值

so set remove duplicate value automatically

在您的代碼中，您有數組而不是轉換數組以直接使用代碼設置

and in your code you have array than convert array to set directly using code

Set<T> mySet = new HashSet<T>(Arrays.asList(someArray));

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