CODEWITHSUNDEEP
javafilewriterreader
Janek Sławiński
Janek Sławiński

Reputation: 39

Why can't I neither delete nor rename the file?

While creating a method to my class, I got an unexpected problem. I've tried solutions from other theards, but they just don't work for me. My method should simply find the line specified, copy the file skipping unnecessary line, delete the original file and rename temporary file to the name of original file. It succesfuly creates new file as expected, but then fails to delete previous one as it fails to rename temporary file to original. I can't figure out, why?

void lineDelete(String file_name, String line_to_erase){
    try {
        int line_number = 0;
        String newline = System.getProperty("line.separator");
        File temp = new File("temporary.txt");
        File theFile = new File(file_name+".txt");
        String path = theFile.getCanonicalPath();
        File filePath = new File(path);

        BufferedReader reader = new BufferedReader(new FileReader(file_name + ".txt"));
        BufferedWriter writer = new BufferedWriter(new FileWriter(temp));

        String lineToRemove = line_to_erase;
        String currentLine;

        while((currentLine = reader.readLine()) != null) {
            String trimmedLine = currentLine.trim();
            if(trimmedLine.equals(lineToRemove)){
                continue;
            }
            writer.write(currentLine + newline));
        }
        writer.close(); 
        reader.close();
        filePath.delete();
        temp.renameTo(theFile);
    }
    catch (FileNotFoundException e){
        System.out.println(e);
    }
    catch (IOException e){
        System.out.println(e);
    }

Upvotes: 1

Views: 264

Answers (2)

Stephen C
Stephen C

Reputation: 719336

I could suggest a couple of reasons why the delete and/or rename might fail, but there is a better way to solve your problem than guessing1.

If you use Path and the Files.delete(Path) and Files.move(Path, Path, CopyOption...) methods, they will throw exceptions if the operations fail. The exception name and message should give you clues as to what is actually going wrong.

The javadoc is here and here.

1 - Here are a couple of guesses: 1) the file has been opened elsewhere, and it is locked as a result. 2) You don't have access to delete the file.

Upvotes: 1

Ricardo
Ricardo

Reputation: 9686

Try this code:

void lineDelete(String file_name, String line_to_erase){
try {
    int line_number = 0;
    String newline = System.getProperty("line.separator");
    File temp = new File("temporary.txt");
    File theFile = new File(file_name+".txt");
    String path = theFile.getCanonicalPath();

    BufferedReader reader = new BufferedReader(new FileReader(theFile));
    BufferedWriter writer = new BufferedWriter(new FileWriter(temp));

    String lineToRemove = line_to_erase;
    String currentLine;

    while((currentLine = reader.readLine()) != null) {
        String trimmedLine = currentLine.trim();
        if(trimmedLine.equals(lineToRemove)){
            continue;
        }
        writer.write(currentLine + newline));
    }
    writer.close(); 
    reader.close();
    theFile.delete();
    temp.renameTo(file_name + ".txt");
}
catch (FileNotFoundException e){
    System.out.println(e);
}
catch (IOException e){
    System.out.println(e);
}

Upvotes: 1

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