java RandomAccessFile parameter

Question

I am trying to follow the below example found it here Java: Find if the last line of a file is empty to determine if a file finish by CRLF(empty line) however when I pass a String to the method RandomAccessFile says file Not Found. the problem is I cant feed it the file path, but I have the contents of the file as a String, so I tried to create a file using File f = new File(myString); and then pass the method the created file but it didnt work and it gave me the same error (File not Found) (it consideres the first line of the file as the path)!

how can I create a file accepted by RandomAccessFile, from my String that contains the contents of the file I want to check if it finishs by CRLF.

Hope I was clear.

public static boolean lastLineisCRLF(String filename) {
    RandomAccessFile raf = null;
    try {
        raf = new RandomAccessFile(filename, "r");
        long pos = raf.length() - 2;
        if (pos < 0) return false; // too short
        raf.seek(pos);
        return raf.read() == '\r' && raf.read() == '\n';
    } catch (IOException e) {
        return false;
    } finally {
        if (raf != null) try {
            raf.close();
        } catch (IOException ignored) {
        }
    }
}

the user selects a file by a jsp. I store the file name and the content in a String. meaning I have the selected file name and contents. — Laetitia Zgraja, Jul 09 '13 at 16:56
when it says file Not Found, it really means file not found. possibly you pass the file path wrong — , Jul 09 '13 at 21:06

lreeder · Accepted Answer · 2013-07-09T17:08:28.510

0

If you have the file contents already in memory as a string, you don't need to write it to a file again to determine if the last line is empty. Just split the contents by an end-of-line character and then trim whitespace off the last line and see if anything is left:

  String fileContent = "line1\nline2\nline3\nline4\n";
  // -1 limit tells split to keep empty fields
  String[] fileLines = fileContent.split("\n", -1);
  String lastLine = fileLines[fileLines.length - 1];
  boolean lastLineIsEmpty = false;
  if(lastLine.trim().isEmpty())
  {
     lastLineIsEmpty = true;
  }

  //prints true, line4 followed by carriage return but 
  //no line 5
  System.out.println("lastLineEmpty: " + lastLineIsEmpty);

edited Jul 09 '13 at 17:08

answered Jul 09 '13 at 16:58

lreeder

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nice idea! I tried it I have 2 errors The method fileLines(int) is undefined; The method isEmpty() is undefined for the type String – Laetitia Zgraja Jul 09 '13 at 17:08
@LaetitiaZgraja My code was buggy, but I think it's fixed now. Check the most recent edits. – lreeder Jul 09 '13 at 17:19
P.S the last of the file has no white spaces. the file is finished by CRLF. – Laetitia Zgraja Jul 09 '13 at 17:20
Also, isEmpty() was added to String, in Java 1.6. If you are not using 1.6, you can replace isEmpty() with `lastLine.trim().length() == 0` – lreeder Jul 09 '13 at 17:21
if(lastLine.trim().isEmpty()) gives the error The method isEmpty() is undefined for the type String – Laetitia Zgraja Jul 09 '13 at 17:21
@LaetitiaZgraja If your file is in the format "line1\r\nline2\r\n\r\n", it has four lines, where line3 and line4 are empty. If you want to see if line3 is empty, pull the next-to-last line instead of last line from the fileLines array with `fileLines[fileLines.length - 2];` – lreeder Jul 09 '13 at 17:38

java RandomAccessFile parameter

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