Question

I am writing an updater. I have this code:

package main;
import java.io.*;
import java.net.*;
import java.util.*;
import java.util.regex.Pattern;
import java.lang.*;

import static java.lang.System.out;
public class UpdaterCore
{
public static void main(String args[]) throws IOException
{
    java.io.BufferedInputStream inv = new java.io.BufferedInputStream(new

                    java.net.URL("http://unicombox.tk/update/nv").openStream());
                    java.io.FileOutputStream fosv = new java.io.FileOutputStream("nv");
                    java.io.BufferedOutputStream boutv = new BufferedOutputStream(fosv,1024);
                    byte data[] = new byte[1024];
                    while(inv.read(data,0,1024)>=0)
                    {
                    boutv.write(data);
                    }
                    boutv.close();
                    inv.close();
                    //end version download

                    Scanner VersionReader= new Scanner(new File ("v")).useDelimiter(",");
                    int currentVersion= VersionReader.nextInt();
                    VersionReader.close();

                    Scanner NewVersionReader= new Scanner(new File ("nv")).useDelimiter(",");
                    int newVersion= NewVersionReader.nextInt();
                    NewVersionReader.close();



                    if (newVersion>currentVersion){


                    java.io.BufferedInputStream in = new java.io.BufferedInputStream(new

                                    java.net.URL("http://unicombox.tk/update/update.zip").openStream());
                    java.io.FileOutputStream fos = new java.io.FileOutputStream("update.zip");
                    java.io.BufferedOutputStream bout = new BufferedOutputStream(fos,1024);
                    byte data1[] = new byte[1024];
                    while(in.read(data1,0,1024)>=0)
                    {
                            bout.write(data1);
                    }
                    bout.close();
                    in.close();
                    out.println("Update successfully downloaded!");

                    }

                    else{
                            out.println("You have the latest version!");
                    }








}
}

It gets the new version from a server, and then compares it to its current version. If the new version is greater than the current version, it downloads the update.

I am having one big problem. My program can never find the files “v” and “nv”!
“v” and “nv” are in the same folder as the compiled jar, yet I get a FileNotFound.
What am I doing wrong?

Answer 1

Get path to current directory (directory where the .jar file is placed) like this:

// import java.io.*;
// import java.net.URLDecoder;
// throws java.io.UnsupportedEncodingException 

    String path = UpdaterCore.class.getProtectionDomain().getCodeSource().getLocation().getPath();
    String decodedPath = URLDecoder.decode(path, "UTF-8");
    System.out.println(decodedPath);

and then create File instance like this

new File (decodedPath + File.separatorChar + "v")