重复行筛选器不起作用

Question

我有这段代码，我已经看过很多次了。它似乎过滤了很多，但有些重复可以通过？

import java.io.*;
import java.util.*;
class ipstoblockfilter {
    public static void main(String[] args) throws FileNotFoundException {
        File file = new File("E:\alp\ipstoblock.txt");
       try {
           Scanner sc = new Scanner(file);
 try
    {
PrintWriter printWriter = new PrintWriter("E:\alp\ipstoblockfiltered.txt");
           while (sc.hasNextLine()) {
               String nextLine = sc.nextLine();
               Scanner nextLineParser = new Scanner(nextLine);
               // check if duplicate
                       File filefiltered = new File("E:\alp\ipstoblockfiltered.txt");
       try {
           Scanner scff = new Scanner(filefiltered);
           List<String> arrayList = new ArrayList<String>();
           while (scff.hasNextLine())  {
           arrayList.add(scff.nextLine());
           } //While

     if (!arrayList.contains(nextLine)) {
     printWriter.println(nextLine);
     }
           } //duptry
                  catch (FileNotFoundException e) {
           e.printStackTrace();
           } //dupcatch

               // check if duplicate

           } //while
           printWriter.close();
           }
               catch (FileNotFoundException ex)  
    {
           }
           sc.close();
       } 
       catch (FileNotFoundException e) {
           e.printStackTrace();
       }
    } //Main
} // Class

这怎么可能？

如果有什么需要我研究或改变的地方，请告诉我！

谢谢你的帮助！

编辑：

所以我尝试了andrewdleach的代码，并产生了以下错误

[错误]

ipstoblockfilter.java:7: error: incompatible types: File cannot be converted to Reader
BufferedReader reader = new BufferedReader(file);
                                           ^
ipstoblockfilter.java:15: error: cannot find symbol
Printwriter writer = new PrintWriter(file);
^
  symbol:   class Printwriter
  location: class ipstoblockcommands
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
2 errors

[/error]

这是我试过的他的密码[代码]

import java.io.*;
import java.util.*;
class ipstoblockcommands {
    public static void main(String[] args) throws FileNotFoundException {
File file = new File("E:\alp\ipstoblock.txt");
BufferedReader reader = new BufferedReader(file);
Set<String> lineSet= new HashSet<>();
while (reader.readLine() != null) {
    lineSet.add(reader.readLine().trim());
}
reader.close();
Printwriter writer = new PrintWriter(file);
Iterator<String> iterator = lineSet.iterator();
while (iterator.hasNext()) {
    writer.write(iterator.next());
}
writer.close();

    } //Main

} // Class

[/code]

Answer 1

从代码中，您一次分析一行，如果Arraylist不包含您的行，则使用PrintWriter进行编写。好的

但是，您正在尝试同时从同一文件读取和打印。

相反，将每一行读取到Strings的数据结构中，删除重复项，然后在对所有适当的数据进行排序和解析后写回文件。

编辑：

import java.io.*;
import java.util.*;
public class IpScanner {
public IpScanner() {
} 
private void start() {
    try {
        File file = new File("FILE_PATH\ipstoblock.txt");
        BufferedReader reader = new BufferedReader(new FileReader(file));
        Set<String> lineSet= new HashSet<>();
        while (reader.readLine() != null) {
            lineSet.add(reader.readLine().trim());
        }
        reader.close();
        PrintWriter writer = new PrintWriter(file);
        Iterator<String> iterator = lineSet.iterator();
           while (iterator.hasNext()) {
               writer.write(iterator.next() + "rn");
        }
        writer.close();
    } catch (IOException e) {
        System.err.println("Couldn't parse");
    }
    }
    public static void main(String[] args){
        new IpScanner().start();
   } 
}