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Aug 3rd, 2007

Can JAVA create DOS directories?

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After my poor showing yesterday I was ready to quit, but I decided this morning I would rather feel dumb than feel like a quitter, so here I am.

I coded this last night thinking if it worked great, if not then I would just drop it. Well it worked ... kind of.

I want to write my JList to a file on the harddrive, so I created a button that does this, and the file is created just fine, in the same directory as all my classes and java files. Not where I want it. I tried changing the path to a c:\data\ directory, but my method will not put the file there, even if I manually create the directory it will not do it.

Java Syntax (Toggle Plain Text)
	private void btnSaveActionPerformed(ActionEvent evt)
		{
			FileOutputStream out; // declare a file output object
			PrintStream p; // declare a print stream object
 
			try
				{
				// create a new file output stream
				// connected to "myfile.txt"
				out = new FileOutputStream("inventory.dat");	
 
				// connect print stream to the output stream
				p = new PrintStream(out);
 
				p.println (listModel);
				p.close();
			   }
 
				catch (Exception e)
				{
				System.err.println ("Error writing to file");
				}
		}// end SAVE
	private void btnSaveActionPerformed(ActionEvent evt)
		{
			FileOutputStream out; // declare a file output object
			PrintStream p; // declare a print stream object
			
			try
				{
				// create a new file output stream
				// connected to "myfile.txt"
				out = new FileOutputStream("inventory.dat");	
				
				// connect print stream to the output stream
				p = new PrintStream(out);
				
				p.println (listModel);
				p.close();
			   }
			
				catch (Exception e)
				{
				System.err.println ("Error writing to file");
				}
		}// end SAVE

Why can I not change location of my output? And if I can, can I make JAVA create the directory for me if it is not already there?

no1zson

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

this is your problem out = new FileOutputStream("inventory.dat");.
Try this and see what happends out = new FileOutputStream("C:" + File.separator + "inventory.dat");

peter_budo

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

Just for future reference, you can't give Java a relative reference to a file and expect it to create a file with an absolute reference.

"inventory.dat" will be created in the folder that you are running java from (relative reference, relative to the creating location)

"C:\inventory.dat" will be created in the C: (absolute reference, doesn't matter where the creator is)

TheGathering

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

Thanks for the tip on relative and absolute references.
I added to your line with this:

Java Syntax (Toggle Plain Text)
out = new FileOutputStream("C:" + File.separator + "data" + File.separator + "inventory.dat");
out = new FileOutputStream("C:" + File.separator + "data" + File.separator + "inventory.dat");

In order to get it down one more level into my DATA folder. It works, as long as the data folder is present upon execution.

Can I not make Java create that folder if it is not already present?

no1zson

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

Java Syntax (Toggle Plain Text)
    public void createFile(String in)
    {
      toWork = new File(in);
      try
      {
      if(toWork.exists() == false)
      {
        System.out.println("DNE");
        toWork.createNewFile();
      }
      if(toWork.canRead() == false)
      	System.out.println("Read error.");
      if(toWork.canWrite() == false)
      	System.out.println("Write error.");
      }
      catch(Exception e){}
    }
    public void createFile(String in)
    {
      toWork = new File(in);
      try
      {
      if(toWork.exists() == false)
      {
        System.out.println("DNE");
        toWork.createNewFile();
      }
      if(toWork.canRead() == false)
      	System.out.println("Read error.");
      if(toWork.canWrite() == false)
      	System.out.println("Write error.");
      }
      catch(Exception e){}
    }

That was an handling function I had for an old network isntant messaging program I wrote. Try doing the same thing, creating the FileOutputStream object from a File object after checking if the directory/file exists. If it doesn't exist, use the "mkdir()" method from File to create the directory.

Last edited by TheGathering; Aug 3rd, 2007 at 12:02 pm.

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

Something new. It did not error durning compile. good sign. It did not error during test run, another good sign.
It did not create file or directory either though!

I have done a lot of wrong stuff out here, but I cannot wait to see how I managed this.

Java Syntax (Toggle Plain Text)
// SAVE		
		private void btnSaveActionPerformed(ActionEvent evt)
		{
 
			File toWork = new File("C:" + File.separator + "data" + File.separator + "inventory.dat");
 
 
			try
				{
				if(toWork.exists() == false)// if file and directory do not exist
				{
				toWork.mkdir();// make directory
				toWork.createNewFile();  // create file 
				System.out.println(listModel);  // print list to file
							   }
				if(toWork.canRead()== false) 
					System.out.println("Read Error.");
				if(toWork.canWrite() == false) 
					System.out.println("Write error.");
				}
				catch (Exception e){}
 
 
		}// end SAVE
// SAVE		
		private void btnSaveActionPerformed(ActionEvent evt)
		{
			
			File toWork = new File("C:" + File.separator + "data" + File.separator + "inventory.dat");

					
			try
				{
				if(toWork.exists() == false)// if file and directory do not exist
				{
				toWork.mkdir();// make directory
				toWork.createNewFile();  // create file 
				System.out.println(listModel);  // print list to file
							   }
				if(toWork.canRead()== false) 
					System.out.println("Read Error.");
				if(toWork.canWrite() == false) 
					System.out.println("Write error.");
				}
				catch (Exception e){}
			
				
		}// end SAVE

p.s. I tried the file name both ways, just incase I misunderstood what you told me earlier.

Last edited by no1zson; Aug 3rd, 2007 at 1:02 pm.

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

No, Java can't create directories under DOS for the very simple reason that Java doesn't work under DOS.

jwenting

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duckman

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

I am most confused then, because I am supposed to use exception handling to create the file and directory if they do not exist.

Maybe I will just put up a message if it is not there telling the user to create it manually and then try again.

no1zson

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

Actually, as I continued to play with it I DID get it to create my data directory by altering this line.
File toWork = new File("C:" + File.separator + "data");

Only problem is that my string now prints to the screen in stead of a file.

no1zson

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Aug 3rd, 2007

Re: Can JAVA create DOS directories?

OK, with the fileoutput stream I was able to write the file, but not create the directory.
With the new File statement I am able to create the directory but not write the file.

When I put both in, neither works.

Anyone?

no1zson

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