Java Answers Forum - Lookup table & multiple jars

Articles |
News |
Weblogs |
Books |
Forums

Artima Forums | Articles | Weblogs | Java Answers | News

Sponsored Link •

Java Answers Forum
Lookup table & multiple jars

2 replies on 1 page. Most recent reply: May 22, 2003 7:24 AM by Michael

Welcome Guest
Sign In

Back to Topic List

Reply to this Topic

Search Forum

Threaded View


Previous Topic		Next Topic

Flat View: This topic has 2 replies on 1 page

Michael

Posts: 4
Nickname: yaruki
Registered: May, 2003

Lookup table & multiple jars

Posted: May 20, 2003 7:26 PM

I need to implement a class to essentially become a huge lookup table (12k entries) - I feed it a "key" and it returns a value.

1) What is the best way to do this - just build a big HashMap?

2) To initialize it, I'm planning on loading the data from a tab-delimited text file, but I'm a little confused about where that file should live and how I should point my class to it.

3) Related to the previous point, this class will be packaged in a jar that is one of several jars to be passed in through the command line classpath to launch the application. I don't really understand how the "virtual filesystems" represented in each jar relate to each other, and what kind of views of the various namespaces are available to classes in the various jars.

I hope that some of you Java gurus can enlighten me or point me at some resources where I can learn more about these sorts of things.

Thanks!

Jaycee

Posts: 26
Nickname: jaycee
Registered: Apr, 2003

Re: Lookup table & multiple jars

Posted: May 21, 2003 9:00 AM

> 1) What is the best way to do this - just build a big
> HashMap?

If your keys and values are both Strings, use a Properties object.

>
> 2) To initialize it, I'm planning on loading the data from
> a tab-delimited text file, but I'm a little confused about
> where that file should live and how I should point my
> class to it.

Create a lookup.properties file which uses a name=value format instead of tab-delimited. You can put this properties file anywhere, as long as the path is specified when creating the FileInputStream. If you just want to specify the properties file name, and not the full path, you can put it in the same package as the code loading the Properties object.

e.g. one line from lookup.properties
country=Canada

Properties lookupTable = new Properties();
lookupTable.load(new FileInputStream("lookup.properties));

>
> 3) Related to the previous point, this class will be
> packaged in a jar that is one of several jars to be passed
> in through the command line classpath to launch the
> application. I don't really understand how the "virtual
> filesystems" represented in each jar relate to each other,
> and what kind of views of the various namespaces are
> available to classes in the various jars.

I believe there are some good articles on class loading on the Artima site.

Michael

Posts: 4
Nickname: yaruki
Registered: May, 2003

Re: Lookup table & multiple jars

Posted: May 22, 2003 7:24 AM

Jaycee,

>If your keys and values are both Strings, use a Properties object.
Thanks a lot for replying, I really appreciate it. I used that trick once for another project, but it feels like kind of a kludge in this case and a violation of the properties semantics as I understand them. (Or maybe I just have delicate sensibilities :)

Actually, I'm doing a two-stage lookup for natural language processing/corpus linguistics. I want to look a word token up in a list and return the corresponding lemma from a table, and then look up that lemma in a table to get its frequency ranking (an integer, not a string value).

>You can put this properties file anywhere, as long as the path is
>specified when creating the FileInputStream. If you just want to
>specify the properties file name, and not the full path, you can put
>it in the same package as the code loading the Properties object.
That's what I don't understand - what if two of the jars collide with a file or folder name? How can put a text file in a "package"? Do you mean jar?

Still a little hazy, sorry for being so dense.

Flat View: This topic has 2 replies on 1 page

Previous Topic

Next Topic


	Web Artima.com