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About properties file

Posted on 2003-11-24
Last Modified: 2013-11-23
I am working on java applet and all .class files, images and text files will be loaded from the
applet archive attribute jar file named your_login.jar. My
program will first load a configuration file named library.properties
from my classpath /config/library.properties. From there my
program will load the employees.txt and books.txt file also in the
config subdirectory - see below jar file content. I am not supposed
employee/book values but instead read them in at runtime using the
following files: employees.txt and books.txt that I should include
in my jar file config directory. I know that I could
use this.getClass().getResource("/config/library.properties");
to get a URL to the file located at config/library.properties
in my jar file. I think I need to use getResourceAsStream to get an InputStream
to that resource.

your_login.jar (library jar file loaded by applet) contains the following:

jar xvf your_login.jar will create relative to the current directory:

My question is how my library.properties file should be?


Question by:dkim18
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Assisted Solution

DidierD earned 20 total points
ID: 9816284
LVL 14

Expert Comment

by:Tommy Braas
ID: 9816288
If your question is how to format your properties file, then the following is the format:


Here is an example;


Don't forget that the same characters that you would escape in s String constant in Java, also needs to be escaped in your properties file.
LVL 92

Expert Comment

ID: 9816289
Properties props = new Properties();

And your properties file should be in the format:

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Author Comment

ID: 9827188
I did the following, but I got FileNotFoundExcetion error.

In my readEmployeeFile() fuction:

Properties props = new Properties();
String bookResource = props.getProperty("books");

inFile = new BufferedReader(new InputStreamReader(this.getClass().getResourceAsStream(bookResource)));

and inside of library.properties:


I also created library.properties solaris system and ftp into my home pc because I was told library.properties shouldn’t .txt format. I tried changing library.properties executable file too, but wasn’t successful.
In my config dir, books.txt and employees.txt are located, but I shouldn’t hardcode like this:
inFile = new BufferedReader(new

but instead read them from the library.properties

What am I doing wrong?
LVL 14

Assisted Solution

by:Tommy Braas
Tommy Braas earned 80 total points
ID: 9827423
Try using:

   public URL Class.getResource(String name)

and see what the URL is pointing to by calling either toString() or toExternalForm().

According to the Javadocs on getResource:

"Finds a resource with a given name. This method returns null if no resource with this name is found. The rules for searching resources associated with a given class are implemented by the * defining class loader of the class.

This method delegates the call to its class loader, after making these changes to the resource name: if the resource name starts with "/", it is unchanged; otherwise, the package name is prepended to the resource name after converting "." to "/". If this object was loaded by the bootstrap loader, the call is delegated to ClassLoader.getSystemResource. "
LVL 92

Accepted Solution

objects earned 150 total points
ID: 9827674
WHere exactly are you getting the error, and where are your properties and txt files located?

> books="classes\config\books.txt"
> employees="classes\config\employees.txt"

should perhaps be:



Author Comment

ID: 9828127

this solved the problem.
Thank you so much...
LVL 92

Expert Comment

ID: 9828148

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