I want to read the data from txt, then I will remove the header of the txt and save the data into and array every 2 line, cause it still continues data.

• visitor.txt

    1                   DAILY REPORT VISITOR
                            DATE : 02-02-22
    0 ------------------------------------------------------------------ 
        NO.     DATE            NAME                ADDRESS
        PHONE           BIRTHDAY        NEED                              
      ------------------------------------------------------------------ 
          1     02-02-22        ELIZABETH ZEE       WASHINGTON DC
         32 62          18-10-1985      BORROW BOOK
          2     02-02-22        VICTORIA GEA        BRUSEELS
         32 64          24-05-1986      VISITOR
          3     02-02-22        GEORGE PHILIPS      BRUSEELS
         32 76          02-05-1990      VISITOR 

so, i want the data that save into an array like this.

1       02-02-22        ELIZABETH ZEE       WASHINGTON DC        32 62          18-10-1985      BORROW BOOK
2       02-02-22        VICTORIA GEA        BRUSEELS             32 64          24-05-1986      VISITOR
3       02-02-22        GEORGE PHILIPS      BRUSEELS             32 76          02-05-1990      VISITOR

and this is the code

BufferedReader bR = new BufferedReader(new FileReader(myfile));
int i =0;

String line;
        
try {
    while (line = bufferedReader.readLine()) != null) {
    i  ;
    String data = line.split("\\s", "")

    if(data.matches("[0-9]{1,3}\\s. ")) {
        String[] dataArray = data.split("\\s", -1);
        String[] result = new String[30];

        System.arraycopy(fileArray, 0, result, 0, fileArray.length);

        String data1 = line.get(i).split("\\s", "")
        String[] fileArray1 = data.split("\\s", -1);
        String[] result1 = new String[30];
 
        System.arraycopy(fileArray1, 0, result1,0,fileArray1.length);       
    }
    
}

The problem here is, i think this code is not effective cause it will be read the second line twice from data and data1. I want every 2 lines will save into one row in the database like the result of txt. Do you have any solution ? I need your help. Thanks :)

CodePudding user response：

It seems unlikely for me that one line would be read multiple times. Try to debug your code to see if that actually happens.

Otherwise, you could really skip the first line before starting processing:

BufferedReader bR = new BufferedReader(new FileReader(myfile));
int i =0;

String line;
    
try {
    // alternative one
    String firstline = bufferedReader.readLine();
    String secondline = bufferedReader.readLine();
    String mergedline = firstline   secondline; // the linefeed should have been removed but the data is retained

    // alternative two
    StringBuilder sb = new StringBuilder();
    sb.append(bufferedReader.readLine()); // first line
    sb.append(bufferedReader.readLine()); // second line
    ... = sb.toString(); // now do something with the merged lines

    // the other stuff
    while (line = bufferedReader.readLine()) != null) {
        // process your data lines here
    }

}

CodePudding user response：

• The result has actually a dynamic number of records. Then a fixed size array no longer is suitable. Use List<String\[\]> instead: list.add(stringArray), list.get(i), list.size(), list.isEmpty().
• The header seems to consist of 2 lines, but I may err.
• I saw fields with a space, hence one cannot split on \s (one or more whitespace characters). I did split on \s\s . Maybe you should better use the fixed length field boundaries with line1.substring(i1, i2).
• FileReader uses the encoding on your current computer (=unportable file). I have made it explicit. If it always an US-ASCII file, without special characters, you could use StandardCharsets.US_ASCII. Then you can run the software on a Linux server, that normally uses UTF-8.

So without check of data format (which however makes sense):

private void stackOverflow() throws IOException {
    List<String[]> data = loadData("mydata.txt");
    System.out.println(data.size()   " records read");
    for (String[] fields: data) {
        System.out.println(Arrays.toString(fields));
    }
}

private List<String[]> loadData(String myFile) throws IOException {
    List<String[]> data = new ArrayList<>();
    Path path = Paths.get(myFile);
    try (BufferedReader bufferedReader =
            Files.newBufferedReader(path, Charset.defaultCharset())) {
        if (bufferedReader.readLine() != null
                && bufferedReader.readLine() != null) { // Skip both header lines.
            String line1, line2;
            while ((line1 = bufferedReader.readLine()) != null
                    && (line2 = bufferedReader.readLine()) != null) {

                String[] fields1 = line1.split("\\s\\s ", 4); // Split on at least 2 spaces.
                if (fields1.length != 4) {
                    throw new IOException("Wrong number of fields for first line: "   line1);
                }
                String[] fields2 = line2.split("\\s\\s ", 3); // Split on at least 2 spaces.
                if (fields1.length != 3) {
                    throw new IOException("Wrong number of fields for second line: "   line2);
                }
                String[] total = Arrays.copyOf(fields1, 7);
                System.arraycopy(fields2, 0, total, 4, fields2.length);
                ;
                data.add(total);
            }
            if (line1 != null && !line1.isBlank()) {
                throw new IOException("Trailing single line: "   line1);
            }
        }
    }
    return data;
}

• Substring is better, safer, than split.

• Instead of String[] you might use record class (since java 14)

  record Visitor(String no, String date, String name, String address,
          String phone, String birthday, String need) { }
  List<Visitor> data = new ArrayList<>();
  data.add(new Visitor(fields1[0], fields1[1], fields1[2], fields1[3],
      fields2[0], fields2[1], fields2[3]);
  

A record need little code, however cannot be changed, only replaced in the list.