CODEWITHSUNDEEP
javafileflushfilewriter
Idon89
Idon89

Reputation: 141

Writing to file in java - close or flush

I'm writing a logger to my java program (in csv format) with bufferedWriter and FileWriter.

When i open the csv file while the program is running and continues writing to the file, I got this exception: "The process cannot access the file because it is being used by another process".

What i want is when i open the csv file while the program is running, The csv file will open in read mode and the program will writing successfully to the file.

I solved it by changing the closing of bufferedWriter and FileWriter to .flush() instead of .close()

Original minimal logger code (with the original close function)

public class logger {
     private BufferedWriter bw = null;
     private FileWriter fw = null;
     private File file = null;

   logger(String nclass) {

        path = "c:\\test\\test.csv";
        this.file = new File(path);

        // Check if the file is already exist.
        if (!file.exists()) {
            file.createNewFile();
        }

        fw = new FileWriter(file.getAbsoluteFile(), true);
        bw = new BufferedWriter(fw);
   }
   public void writeToFile(String msg) {
    entryWrite();

    try {

        fw = new FileWriter(file.getAbsoluteFile(), true);
        bw = new BufferedWriter(fw);
        fw.append(msg);

    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        close();
        exitWrite();
    }
}

}

  private void close()  {
try {
    if (bw != null) {
        bw.close(); 
        bw = null;
    }
    if (fw != null) {
        fw.close();
        fw = null;
    }
} catch (IOException ex) {
    ex.printStackTrace();
}

}

My solution function

  private void close()  {
try {
    if (bw != null) {
        bw.flush(); 
        bw = null;
    }
    if (fw != null) {
        fw.flush();
        fw = null;
    }
} catch (IOException ex) {
    ex.printStackTrace();
}

}

Now my answer is if it is ok not to close the stream and just use with flush? Can there be any problems later? Because in all my tests its run well.

Thanks !!

Upvotes: 1

Views: 5492

Answers (1)

Zobs
Zobs

Reputation: 31

Just do bufferedWriter object close.

bw.close();

say, you have a large file.txt. Now u are gonna take something from a file and make a new smaller text file each time. in that case, somehow you have to write some lines of code to determine when you finish writing on a particular file. Then use flag to write bw.close();

eventually, you have to initialize the second file and do your task. then bw.close();

if you don't write fw.close(), then the file will be empty. so, make sure each file writing operation you have to write bw.close()

Upvotes: 0

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