Question

I want to write data to a text file. But, in my application, i will want to keep on writing items to the text file (Which means, the text that i want to write, should be appended to the file – and not create a new file every time)

My code, is as follows; But how could i append text the next time i am writing something to the file ?

1.) The problem with the code below is, the first time writes to the file, but when i am trying to write for the 2nd time i get the following exception;

java.io.IOException: Stream closed

2.) I want to be able to write to the same file untill the application is closed. Therefore, how can i close the Stream when the application is closed ?

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class WriteToFileExample {
    public void writeToFile(String stuff) {
        try {
                File file = new File("../somefile.txt");

            if (!file.exists()) {
                file.createNewFile();
            }

            FileWriter fw = new FileWriter(file.getAbsoluteFile(),true);
            BufferedWriter bw = new BufferedWriter(fw);
            bw.write(stuff);
            bw.close();


        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

UPDATE 1

private File file;
public WriteToFileExample(){
                 file = new File("../somefile.txt");

}


public void writeToFile(String stuff) {
            try {


                if (!file.exists()) {
                    file.createNewFile();
                }

                FileWriter fw = new FileWriter(file.getAbsoluteFile());
                BufferedWriter bw = new BufferedWriter(fw);
                bw.write(stuff);
                bw.close();


            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

EXCEPTION

Exception in thread "main" java.lang.NullPointerException
    at com.proj.example.Log.WriteToFile(WriteToFileExample.java:3)

Which points to if (!file.exists()) {.

Answer 1

You never close the FileWriter in your code. And from the documentation for the class:

Whether or not a file is available or may be created depends upon the
underlying platform. Some platforms, in particular, allow a file to be
opened for writing by only one FileWriter (or other file-writing
object) at a time. In such situations the constructors in this class
will fail if the file involved is already open.

Close the file writer before exiting your method, its good practice anyway. And yes, definitely do open the writer in append mode, if you don’t want the files contents to be blown away every time you call your method.