java - 如何通过java过滤文本文件并将结果保存到新文件

Question

您好，我的问题是如何按列过滤文本文件，我的意思是我想从行之间的范围中剪切文件。 我的文件包含此类数据:

284015160747447;8935901990807474474;
284015160747448;8935901990807474482;
284015160747449;8935901990807474490;
284015160747450;8935901990807474508;
284015160747451;8935901990807474516;
284015160747452;8935901990807474524;
284015160747453;8935901990807474532;
284015160747454;8935901990807474540;
284015160747455;8935901990807474557;
284015160747456;8935901990807474565;
284015160747457;8935901990807474573;
284015160747458;8935901990807474581;
284015160747459;8935901990807474599;
284015160747460;8935901990807474607;
284015160747461;8935901990807474615;
284015160747462;8935901990807474623;
284015160747463;8935901990807474631;

我希望用户能够过滤要从原始文件写入新创建的内容: 例如从 8935901990807474490 到 8935901990807474532，对于此数字，起始行和最后一行应在此范围内。

public class Test_read_file {
    public static List<String> readFile() throws IOException {
        try (BufferedReader br = new BufferedReader(new FileReader("C:\\\\\\\\Users\\\\\\\\Admin\\\\\\\\Desktop\\\\\\\\Work Files\\\\\\\\314-WO0000001133814\\\\\\\\Cards\\\\\\\\MBD10760_182.out"))) {
            List<String> listOfData = new ArrayList<>();
            String d;
            while ((d = br.readLine()) != null) {
                listOfData.add(d);
            }
            return listOfData;
        }
    }

    public static void writeFile(List<String> listOfData) throws IOException {
        try (BufferedWriter bw = new BufferedWriter(new FileWriter("C:\\\\\\\\Users\\\\\\\\Admin\\\\\\\\Desktop\\\\\\\\Work Files\\\\\\\\314-WO0000001133814\\\\\\\\Cards\\\\\\\\MBD10760_187.out"))) {
            for (String str : listOfData) {
                bw.write(str);
                bw.newLine();
            }
        }
    }

    public static void main(String[] args) throws IOException {
        List<String> data = readFile();
        writeFile(data);
    }
}

Answer 1

对您的代码进行以下更改:

1. 使用扫描仪接受要过滤的值:

   public static void main(String[] args) throws IOException {
       List<String> data = readFile();         
       Scanner sc = new Scanner(System.in);        
       System.out.println("Enter range");      
       long num1 = sc.nextLong();      
       long num2 = sc.nextLong();      
       writeFile(data, num1, num2);
       sc.close();     
   }
   

2. 因为您只想由第二列写入列，所以将其拆分 使用 ; 然后仅将第一个索引添加到列表中。这可确保仅第二列的数字被添加到列表中。

   public static List<String> readFile() throws IOException {      
       try (BufferedReader br = new BufferedReader(new FileReader(PATH))) {
           List<String> listOfData = new ArrayList<>();            
           String d;
           while ((d = br.readLine()) != null) {
               String[] split = d.split(";");  // <-- change made here
               listOfData.add(split[1]);           
           }           
           return listOfData;      
        }  
   }
   

3. 使用传入的范围，它只会写入属于该范围的数字 在此范围内。

   public static void writeFile(List<String> listOfData, long num1, long num2) 
      throws IOException {
      try (BufferedWriter bw = new BufferedWriter(new FileWriter(OUT))) {          
           for (String str : listOfData) {
               // change made here
               if (Long.valueOf(str) >= num1 && Long.valueOf(str) <= num2) {
                   bw.write(str);
                   bw.newLine();
               }           
           }       
       }   
   }