Writing numbers to a Java file

Question

Writing numbers to a Java file

I write the array elements to the file

try (FileWriter writer = new FileWriter("C:\\prg1\\Letter.txt", false);) { 
     for(int i=0;i<mas.length;++i){
         writer.write(mas[i]);
         writer.write(System.lineSeparator());
     }
} catch(IOException ex){
     System.out.println(ex.getMessage());
}

The problem is that in the source file "Letter.txt" there are incomprehensible characters instead of numbers. Can you somehow specify the encoding when writing numbers ?

1

java encoding

Author: Slava Vedenin, 2016-01-13

Source

3 answers

score 2 · Answer 1

The java.io.FileWriter.write method writes to the file not a string representation of a number, but a character with the code contained in that number. Naturally, strange characters appear in the file. To correctly write a string representation of numbers to a file, you must first get this string representation. To do this, you can use the Integer.toString method. The following code illustrates the application of this technique.

import java.io.*;
import java.util.Random;

class Main 
{
    public static void main(String[] args)
    {
        int[] array = new int[10];
        final Random random = new Random();
        for (int i = 0; i < array.length; ++i)
            array[i] = random.nextInt();

        try (final FileWriter writer = new FileWriter("C:/Temp/Letter.txt", false))
        {
            for (int i = 0; i < array.length; ++i)
            {
                final String s = Integer.toString(array[i]);
                writer.write(s);
                writer.write(System.lineSeparator());
                System.out.println(s);
            }
        }
        catch(IOException e) {
            System.out.println(e.getMessage());
        }
    }
}

score -1 · Answer 2

This is how it will be correct to write:

public static void main(String[] args){

  try {
    File fileDir = new File("c:\\temp\\test.txt");

    Writer out = new BufferedWriter(new OutputStreamWriter(
        new FileOutputStream(fileDir), "UTF8"));

    out.append("some UTF-8 text").append("\r\n");

    out.flush();
    out.close();

    } 
   catch (UnsupportedEncodingException e) 
   {
    System.out.println(e.getMessage());
   } 
   catch (IOException e) 
   {
    System.out.println(e.getMessage());
    }
   catch (Exception e)
   {
    System.out.println(e.getMessage());
   } 
}

score -1 · Answer 3

package javaapplication2;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;


public class JavaApplication2 {


    public static void main(String[] args) {

        ArrayList<Integer> list = new ArrayList<>();
        list.add(13);
        list.add(44);


        try(FileOutputStream out = new FileOutputStream("file")){
            int max = list.size();
            if(max > 0){ // size > 0 
                out.flush();
                //Чистка файла, если надо оставляем

                int i = 0;
                int a;
                while(i<max){
                    if(i > 0){
                        out.write(10); // /n

                        //Выйдет цепочка
                        //13
                        //44
                        //ВНИМАНИЕ! В КОНЦЕ ЛИШНЕГО /N НЕТ
                    }

                    a = list.get(i);

                    out.write(Integer.toString(a).getBytes());


                    i = i + 1;
                }

            }
        } catch (FileNotFoundException ex) {
            Logger.getLogger(JavaApplication2.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(JavaApplication2.class.getName()).log(Level.SEVERE, null, ex);
        }

        //Чтение
        try(FileInputStream in = new FileInputStream("file")){
            //Проще некуда, но на больших файлах это самый плохой вариант
            byte[] buff = new byte[in.available()];
            in.read(buff);

            System.out.write(buff);
            System.out.print(".END....");
            //В конце закрывающий .END....

        } catch (FileNotFoundException ex) {
            Logger.getLogger(JavaApplication2.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(JavaApplication2.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

}

Output:

13
44.END....