Unable to edit Properties file loaded via Class.getResource()

Question

I'm attempting to write a method that will read a properties file using Class.getResource(), make changes to its values, and save the file.

public void saveDBConnectionValues(String user, String password, String host, int port) throws IOException, URISyntaxException
{
    Properties dbProperties = new Properties();

    File f = new File(this.getClass().getResource("db.properties").toURI());

    BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(f))));     

    dbProperties.load(reader);

    reader.close();

    dbProperties.setProperty("user", user);
    dbProperties.setProperty("pw", password);
    dbProperties.setProperty("host", host);
    dbProperties.setProperty("port", Integer.toString(port));

    BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(f)))

    dbProperties.store(writer, null);

    writer.close();

}

My db.properties file is read correctly, but the store method doesn't seem to be working here. Can someone explain why this doesn't work, and what I need to do to get it working?

Thanks

Answer 1

A resource and a file are two different things. A resource is loaded from the class loader, and is found in the classpath. It could be loaded from the file system, or from a jar, or from a socket (or from any other location, depending on the class loader). Writing to a resource doesn't make sense.

If you want to read and write from/to a file, don't use a resource. Use file streams or reader/writer.