Add content to a file without overwriting the content

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Add content to a file without overwriting the content

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#1 by (2 votes)
#2 by (2 votes)

2

I would like to be able to solve the doubt of how to make it possible that when restarting the console do not overwrite and continue writing at the end of the line:

import java.io.*;


public class RedirectSystemOut {

public static void main(String[] args) throws IOException {


    PrintStream console = System.out;
    File file = new File("5.txt");


    FileOutputStream fos = new FileOutputStream(file);

    PrintStream ps = new PrintStream(fos);
    System.setOut(ps);
    System.out.println("This goes to out.txt");

    System.setOut(console);
    System.out.println("This also goes to the console");

  }
 }

Thanks

java filewriter

asked by Nicolás Alarcón R. 09.05.2017 в 12:57

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2 answers

2

Using this constructor, you ensure that the file will be opened in sum mode (append).

FileWriter fw = new FileWriter(file.getAbsoluteFile(), true);

Here is a thread ( link ) with the resolution

answered by 09.05.2017 в 13:03

Default date in an input Up and down volume of an audio channel with the physical buttons on Android

score 2 · Accepted Answer

To avoid overwriting the file, use the class FileWritter and enable the option append (add).

FileWriter fw = new FileWriter(file.getAbsoluteFile(), true); //opción append habilitada!

FileWriter (String fileName, boolean append) :

Parameters:
fileName - String with the file name dependent on the system.

Append - boolean if true , then the data will be written to the end of the file instead of the beginning.

This is an example in which if the file does not exist for the first time, it creates it and then adds the text to the content.

BufferedWriter bw = null;
    FileWriter fw = null;

    try {
        String data = "Hola stackoverflow.com...";
        File file = new File("archivo.txt");
        // Si el archivo no existe, se crea!
        if (!file.exists()) {
            file.createNewFile();
        }
        // flag true, indica adjuntar información al archivo.
        fw = new FileWriter(file.getAbsoluteFile(), true);
        bw = new BufferedWriter(fw);
        bw.write(data);
        System.out.println("información agregada!");
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
                        //Cierra instancias de FileWriter y BufferedWriter
            if (bw != null)
                bw.close();
            if (fw != null)
                fw.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

The result would be a file with name file.txt which will not overwrite the text but will add it to the contents of the file, something similar to:

Hola stackoverflow.com...Hola stackoverflow.com...Hola stackoverflow.com...Hola stackoverflow.com...Hola stackoverflow.com...