Writing 2d int Array to file JAVA

Question

It's been awhile since I've created and written to a file. I've created the file and I've written to it but I get some weird characters. The only numbers that should be in the file are -1, 0, and 1.

Now I get the numbers I need, but I need them to displayed as a 2d array in the text file.

Example:

     -1 -1 -1 -1 -1
     -1 -1 -1 -1 -1
     -1 -1 -1 -1 -1

Please help

public void saveFile()
{
   String save = "Testing";
   JFileChooser fc = new JFileChooser();
   int returnVal = fc.showSaveDialog(null);


    if (returnVal == JFileChooser.APPROVE_OPTION) {
        try {
            FileWriter bw = new FileWriter(fc.getSelectedFile()+".txt");

            for(int row = 0; row < gameArray.length; row++)
           {
               for(int col =0; col < gameArray[row].length; col++)
               {
                  bw.write(String.valueOf(gameArray[row][col]));
               }
           }
            bw.close();

        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

The data is being written: however, you are writing it as binary data. — user2864740
– user2864740, Commented May 1, 2014 at 7:13
It's unclear what you actually need. If you want a text file that contains the textual values of the ints then you need to convert to a String. If not, then you can use a DataOutputStream to write the 4-byte int value. — Brian Roach
– Brian Roach, Commented May 1, 2014 at 7:42

Pshemo · Accepted Answer · 2014-05-01 07:19:39Z

2

From documentation of write(int c) method

Writes a single character. The character to be written is contained in the 16 low-order bits of the given integer value; the 16 high-order bits are ignored.

In other words you are passing index of character from Unicode table.

What you probably need is

fw.write(String.valueOf(gameArray[row][col]));

which will first convert your integer to String and write its characters.

Also consider wrapping your writer with PrintWriter which has methods like print, println (similar to System.out) so you could just use

fw.print(gameArray[row][col]);

answered May 1, 2014 at 7:19

Pshemo

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4 Comments

Pshemo Over a year ago

@user2864740 What do you mean? docs.oracle.com/javase/8/docs/api/java/io/…

user2864740 Over a year ago

Failing on my part. :|

user2906074 Over a year ago

So when you write to files, they're automatically stored as Strings within the file?

Pshemo Over a year ago

@user2906074 Purpose of Writers is writing characters. If you are interested in writing bytes then you should use Streams

An SO User · Accepted Answer · 2014-05-01 07:20:45Z

I suggest that you use a BufferedWriter instead as it is easier.

Writes text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.

Also, you do not need to append a .txt, AFAIK, because JFileChooser will return the full name.

SSCCE:

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

public class WriteToFileExample {
    public static void main(String[] args) {
        try {

            String content = "This is the content to write into file";

            File file = new File("/users/mkyong/filename.txt");

            // if file doesnt exists, then create it
            if (!file.exists()) {
                file.createNewFile();
            }

            FileWriter fw = new FileWriter(file.getAbsoluteFile());
            BufferedWriter bw = new BufferedWriter(fw);
            bw.write(content,0,content.length());
            bw.close();

            System.out.println("Done");

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

taken from Mykong.

Henry · Accepted Answer · 2014-05-01 07:25:23Z

0

Check the documentation, write with an integer argument writes a single character. I guess your gameArray has integer elements.

Convert the elements to a string and also take care to add a space between the numbers. Something like

fw.write(" " + gameArray[row][col]);

will work.

edited May 1, 2014 at 7:25

answered May 1, 2014 at 7:15

Henry

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3 Comments

An SO User Over a year ago

@user2864740 Have a look at my answer.

JB Nizet Over a year ago

@user2864740: by wrapping the FileWriter into a PrintWriter, and using its various print() methods.

An SO User Over a year ago

@JBNizet or just a PrintWriter and avoid the wrapping hassle? :)

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