[Ask] change home directory

[goklien]

anyone know haw to change home directory from java application?

[pbrockway2]

What is a "home directory"?

[goklien]

its how i call default directory where you save your file from your java application

sorry tho im kinda new in java

[pbrockway2]

its how i call default directory where you save your file from your java application

sorry tho im kinda new in java

No need to be sorry - I was just wondering what you meant.

Here's what the File API docs have to say about it. "A pathname, whether abstract or in string form, may be either absolute or relative. An absolute pathname is complete in that no other information is required in order to locate the file that it denotes. A relative pathname, in contrast, must be interpreted in terms of information taken from some other pathname. By default the classes in the java.io package always resolve relative pathnames against the current user directory. This directory is named by the system property user.dir, and is typically the directory in which the Java virtual machine was invoked."

Basically it is saying that a "bare" name will usually be resolved with respect to whatever directory the program is run from. More exactly it will use the value of user.dir

(There is also a user.home property, but it's different)

We can, of course, put the file anywhere we want: either by actually specifying the location absolutely, or by changeing the value of user.dir

Perhaps the code example will make it clear. Ask if not

import java.io.File;

public class Foo {
    public static void main(String[] args) {
            // Fred is in the directory where the program was launched
        System.out.println(new File("fred").getAbsolutePath());
		
            // We change "user.dir" and Fred ends up in the new location
        System.setProperty("user.dir", "C:\\windows");
        System.out.println(new File("fred").getAbsolutePath());
		
            // We specify Fred's location whereever we want it
        System.out.println(new File("H:\\documents\\fred"));
		
            // We put Fred in the users home directory
            // Different operating systems will be different but the
            // home is typically the place where the user puts their stuff
        System.out.println(new File(System.getProperty("user.home"), "fred"));
    }
}

output (for me):
Y:\UserManagement\2011\eclipse\Users\fred
C:\windows\fred
H:\documents\fred
C:\Documents and Settings\pbrockway.GHS\fred

[goklien]

thank you very much

[pbrockway2]

You're welcome.