Escape sequences

[Jon Camilleri]

I'm not sure why I am getting a '/' instead of a '\', when trying to have code sourced from this article, to read from an images sub-directory within my Eclipse IDE project:

 protected static ImageIcon createImageIcon(String path) {
    	//Temporary workaround for current directory
    	String currentPath = System.getProperty("user.dir") + "\\" + path; //hmm...correct?
    	System.out.println("DEBUG: path =" + path);
    	System.out.println("DEBUG: currentPath=" + currentPath);
        java.net.URL imgURL = DialogDemo.class.getResource(currentPath);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }

Output
DEBUG: path =images/middle.gif
DEBUG: currentPathC:\Documents and Settings\Jon\workspace\DialogDemo\images/middle.gif ...It should be \middle.gif I guess, but in any case why do I get the error shown in the following line?
Couldn't find file: images/middle.gif

It seems that similar issues are not intended to be fixed by Sun.

Related articles include this one, and, reference is made to the escape sequences outlined in Core Java Vol I (8th Ed) P.42-43)

[Stephan van Hulst]

Obviously because the path string passed to your method contains a forward slash instead of a backslash.

Where is the code that passes "path" to your method?

[Jon Camilleri]

Stephan van Hulst wrote:Obviously because the path string passed to your method contains a forward slash instead of a backslash.

Where is the code that passes "path" to your method?

Right, sorry

...
public class DialogDemo extends JPanel {
    JLabel label;
    ImageIcon icon = createImageIcon("images\\middle.gif"); 
    JFrame frame;
    String simpleDialogDesc = "Some simple message dialogs";
    String iconDesc = "A JOptionPane has its choice of icons";
    String moreDialogDesc = "Some more dialogs";
    CustomDialog customDialog;
...

[David O'Meara]

have you considered using "images"+File.pathSeparator+"middle.gif"?
(note that the concatenation in this case will likely be managed by the compiler optimization)

[Jon Camilleri]

David O'Meara wrote:have you considered using "images"+File.pathSeparator+"middle.gif"?
(note that the concatenation in this case will likely be managed by the compiler optimization)

Well, I'm not sure because my File.pathSeparator returns ";", and I'm not sure whether I can change the value from the default:

import java.io.*;
import java.lang.*;

public class TestFilePaths
{
	public static void main (String [] args)
	{
		System.out.println(File.pathSeparator);

	}
}

Output
;

[Rob Spoor]

Class.getResource doesn't take an absolute file path the way you are trying to do. It takes a relative path to the current class and uses / for path separator; starting with / makes it an absolute path (relative to the class path, not the current directory).

And David meant File.separator, not pathSeparator.

[Jon Camilleri]

Rob Spoor wrote:Class.getResource doesn't take an absolute file path the way you are trying to do. It takes a relative path to the current class and uses / for path separator; starting with / makes it an absolute path (relative to the class path, not the current directory).

And David meant File.separator, not pathSeparator.

So how may Class.getResource help me with reading the relative path to a string? Any code-snippet, because I couldn't figure it out myself.

import java.io.*;

public class TestFilePaths
{
	public static void main (String [] args)
	{
		System.out.println(File.separator);

	}
}

Output
\

[David O'Meara]

Rob Spoor wrote:And David meant File.separator, not pathSeparator.

Thanks, serves me right for reading a separate section of the API at the same time.

[Rob Spoor]

Jon Camilleri wrote:

Rob Spoor wrote:Class.getResource doesn't take an absolute file path the way you are trying to do. It takes a relative path to the current class and uses / for path separator; starting with / makes it an absolute path (relative to the class path, not the current directory).

And David meant File.separator, not pathSeparator.

So how may Class.getResource help me with reading the relative path to a string? Any code-snippet, because I couldn't figure it out myself.

Assuming the images folder is at the root of your class path:

protected static ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = DialogDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
}

ImageIcon icon = createImageIcon("/images/middle.gif"); // absolute path