Never ever modify: System Property "user.dir"

Newbie & Debugging Questions
#1

I’m such a moron.

You end up with, hairpulling results like this:


writing to rel file: ./hello.txt
writing to abs file: M:\java\workspace\Stuff\new-work-dir\.\hello.txt

file path 1: M:\java\workspace\Stuff\new-work-dir\.\hello.txt
file path 2: M:\java\workspace\Stuff\new-work-dir\hello.txt
file exists at path 1: true
file exists at path 2: false

actual path of file: M:\java\workspace\Stuff\hello.txt
actual path of file: M:\java\workspace\Stuff\new-work-dir\..\hello.txt

See for yourself…


   public static void test() throws IOException
   {
      File newWorkingDirectory = new File("./new-work-dir/");
      newWorkingDirectory.mkdir();

      // change working directory
      {
         String dir = newWorkingDirectory.getCanonicalFile().getAbsolutePath();
         System.out.println("Checking work-directory: " + new File("./").getAbsolutePath());
         System.out.println("=> Setting work-directory to: " + dir);
         System.out.println("=> System.setProperty(\"user.dir\", \"" + dir + "\");");
         System.setProperty("user.dir", dir);
         System.out.println("Checking work-directory: " + new File("./").getAbsolutePath());
      }

      System.out.println();

      // write file
      File f = new File("./hello.txt");
      {
         System.out.println("writing to file: " + f.getAbsolutePath());
         FileOutputStream fos = new FileOutputStream(f);
         fos.write((byte) '3');
         fos.flush();
         fos.close();
      }

      System.out.println();

      // check, check, double-check
      {
         System.out.println("file path 1: " + f.getAbsolutePath());
         System.out.println("file path 2: " + f.getCanonicalFile().getAbsolutePath());
         System.out.println("file exists at path 1: " + f.exists());
         System.out.println("file exists at path 2: " + f.getCanonicalFile().exists());
         System.out.println();
         System.out.println("where the file really ended up: " + new File("../hello.txt").getAbsolutePath());
         System.out.println("where the file really ended up: " + new File("../hello.txt").getCanonicalPath());
      }

      System.out.println();
   }
#2

Haha, this is good to know. :slight_smile: