Java，如何在此输入文本文件之间正确分割多个空白空间？

Question

所以我得到了这份文件：

A-4     09-20-2083  B/2
A/4     04/27/2048  C-2
A/2b     1/24/75    A/4b
A/4     05/07/2049  A/2b
A/2b     7/ 3/31    B/2
A/2b     5/11/53    B-4b
C-4     14-07-2051  A/2
C-2b    22-12-44    A/4
C-4b    11-11-2055  C.2
A/2b     5/11/16    C-2
C.4     08.01.2058  A-4b
B-4b    2010-11- 2  B/2b
B/2b    26/ 3/13    A-4b
C-2     18-06-06    B-4
C.2     08.08.09    C-2
A/2     01/20/99    B-2b
C.4     18.08.2077  B/2
A-4b    10-21-2086  B/4b
B/2b    50/ 2/ 5    A/2
A/4     03/08/2001  A-2b
A/4b    11/ 8/2085  B/4
A/4     03/19/2058  C.2b
A/4b     6/18/2051  B-2
A-4     03-01-2001  B-2b
A-4     02-14-2066  C-4
A/2     06/23/48    A-4
C-4b    18- 8-2065  B/2b
C-2     06-04-94    B/4
B/4b    2057/ 9/21  A-2b
C.2b    21. 8.31    A/2b
A/4b    11/13/2098  A/4
A/2     04/31/63    C-2
B/2b    22/ 5/ 7    A-2
C-4     11-09-2032  B/4b
C.4     08.05.2085  B-2
B-4     2038-10-22  C.4
A/2     03/09/37    C.2b
A/2b     4/ 9/21    A/4
C.2b     3.12.95    B-4
C-4b    26- 1-2004  C-2

如你所见，一些日期或行有随机的空格..。那么，如何使用regex或任何其他读取器正确地读取此输入？非常感谢!

Answer 1

读取文件中的每一行，然后在拆分方法中使用regex“\s+”(多个空格的字符集)分隔它们。

编辑:我的坏消息，没有注意到日期值的空格。您可以使用“{2，}”作为对2个或2个以上空格的正则表达式。

这是从文件中检索每个数据的完整代码。

public static void read(String fileName){
    //create file object
     File file = new File(fileName);
     
     //create file reader
    FileReader fileReader = null ;
    
    //define buffered reader
    BufferedReader bufferedReader = null ;
    
    try {
        fileReader = new FileReader(file);
        bufferedReader = new BufferedReader(fileReader);
        
        String line;
        
        while((line = bufferedReader.readLine()) != null){
            
            //split lines into tokens (values) based on whitespace using regular expression "[ ]{2,}"
            //to indicate two ore more instances of whitespace
            String[] dataArray = line.trim().split("[ ]{2,}");
            
            
        
            //iterate over array of strings
            for(int i = 0 ; i< dataArray.length ; i++) {
                
                //get each value as a string
                String dateString = dataArray[i];
                if(i==1) {
                    System.out.println(dateString);
                }//prints out date in each line 
            }
        }   
    } catch (FileNotFoundException e) {
        // gets and prints filename
        System.out.println("Sorry, " + file.getName() + " not found.");
    } catch (IOException e) {
        // prints the error message and info about which line
        e.printStackTrace();
    }finally {
        
        //regardless, close file objects
        try {
            fileReader.close();
            bufferedReader.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }

}

Answer 2

这里有一个快速而肮脏的解决方案，只需使用扫描仪即可工作。有些边缘情况可能会失败，但至少对给定的输入是这样的，而且对于某些变化的输入，它似乎很好。

import java.util.Scanner;
import java.util.Arrays;

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

    String input =
      "A-4     09-20-2083  B/2\nA/4     04/27/2048  C-2\nA/2b     1/24/75    A/4b\nA/4     05/07/2049  A/2b\nA/2b     7/ 3/31    B/2\nA/2b     5/11/53    B-4b\nC-4     14-07-2051  A/2\nC-2b    22-12-44    A/4\nC-4b    11-11-2055  C.2\nA/2b     5/11/16    C-2\nC.4     08.01.2058  A-4b\nB-4b    2010-11- 2  B/2b\nB/2b    26/ 3/13    A-4b\nC-2     18-06-06    B-4\nC.2     08.08.09    C-2\nA/2     01/20/99    B-2b\nC.4     18.08.2077  B/2\nA-4b    10-21-2086  B/4b\nB/2b    50/ 2/ 5    A/2\nA/4     03/08/2001  A-2b\nA/4b    11/ 8/2085  B/4\nA/4     03/19/2058  C.2b\nA/4b     6/18/2051  B-2\nA-4     03-01-2001  B-2b\nA-4     02-14-2066  C-4\nA/2     06/23/48    A-4\nC-4b    18- 8-2065  B/2b\nC-2     06-04-94    B/4\nB/4b    2057/ 9/21  A-2b\nC.2b    21. 8.31    A/2b\nA/4b    11/13/2098  A/4\nA/2     04/31/63    C-2\nB/2b    22/ 5/ 7    A-2\nC-4     11-09-2032  B/4b\nC.4     08.05.2085  B-2\nB-4     2038-10-22  C.4\nA/2     03/09/37    C.2b\nA/2b     4/ 9/21    A/4\nC.2b     3.12.95    B-4\nC-4b    26- 1-2004  C-2\n";

    Scanner scanner = new Scanner(input);

    while (scanner.hasNextLine())
    {

            String line = scanner.nextLine().trim();

            String[] words = line.split(" ");
            String[] filtered = Arrays.stream(words).filter(s -> !s.isEmpty()).toArray(String[]::new);

            String first = filtered[0].trim ();
            String third = filtered[filtered.length - 1].trim();

            String[] dateArray = Arrays.copyOfRange(filtered, 1, filtered.length - 1);
            String second =  String.join("", dateArray);

            System.out.println (first + "||" + second + "||" + third);
    
   }

   scanner.close();
  }
}

Answer 3

如果你需要快速写作的话..。

String input = Files.readString(Path.of("path\\to\\your\\file.txt"));
//try-catch block omitted
Pattern.compile("(.+?)\\s+(.+?)\\s+(.+?)\\s*\n")
        .matcher(input)
        .results()
        .map(m -> {
            String firstGroupWithLetter = m.group(1);   //"A-4" from first line
            String date = m.group(2);                   //"09-20-2083"
            String secondGroupWithLetter = m.group(3);  //"B/2"
            // m.group(0) is reserved for full match result or kind of that

            // Do whatever you want
            return null;
        })
        // further actions
        ;