Question

尝试编写一个程序，提示用户输入文件名。然后它应该从输入文件中读取整数序列，并打印出整数，删除连续出现的重复值。例如，如果输入文件包含1 2 2 1 5 1 1 7 7 7 7 1 1 1 1 1 1 1 1，则您的程序应打印出1 2 1 5 1 7 1。

我的代码

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++;


        }
      }
   }
}

预期输出为输入文件名：[1,2,1,5,1,7,1] 我得到这个输出输入文件名：1 2 2 1 5 1 1 7 7 7 7 1 1 1 1 1 1 1 1

我不确定如何删除重复的值，但是没有学会如何使用set，所以试图找到一种不同的方式，任何帮助都会很棒:)

Answer 1

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++;
      }
    }
  }  
}

Answer 2

由于您的问题并未完全删除可能已使用Set的重复项，因此您只想删除连续的重复项。因此，您必须跟踪当前的int并将其与下一个内联进行比较，如果匹配则跳过它，否则将其添加到列表中。

以下代码显示了如何执行此操作。你可以用这个替换你的while循环：

   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()));

希望这有帮助。

从文件中删除重复的整数

2 个答案: