Java Create Configuration-like File

Question

I am using Robocode to develop GA tanks that evolve to give better performance (achieving highest fitness levels) and in order to do that I need to store information about each tank in one file.

The class Tank will have several variables such as:

Speed
Angular Momentum
Fire power
Scan Rate

I would like a way to be able to save these variables in a file called "settings.txt" and to be able to update them after a battle.

I would like the file to be formatted like:

robot(1):
speed=12
angMomentum=6
firePower=2
scanRate=10

robot(2):
speed=8
angMomentum=4
firePower=3
scanRate=13

What would be the best way to write a file like this and to be able to easily update the variable values after each battle?

Many Thanks.

score 0 · Accepted Answer · answered Mar 10 '12 at 15:13

If you want all your data in one big file. Maybe it's a good idea to use something like a JSON format because you can maintain your object structure. Use variables, objects and arrays.

There are lots of JSON readers and writers available. Even some 'official' bij json.org to be found here

Your JSON could look like this:

{
    "tanks":[
        {"id": 1, "speed": 12, "angMomentum": 6, "firePower": 2, "scanRate": 10},
        {"id": 2, "speed": 8, "angMomentum": 4, "firePower": 3, "scanRate": 13}
    ]
}

score 0 · Answer 2 · answered Mar 10 '12 at 15:15

0

You should really look into Java Serialization which lets you store and retrieve a plain Java object to disk.

If you really want to create your own custom format you'll have to implement a parser yourself. You can use the java.io and File API to write a String to disk or read from a file e.g., line-by-line.

answered Mar 10 '12 at 15:15

Johan Sjöberg

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1

Serialization is very brittle if you have to maintain those objects in the long term. It's very easy to get wrong when modifying the class later and lose the ability to read in older versions which have already been written. It's really only good for transmitting data over the wire for RMI. – Thorn G Mar 10 '12 at 17:07

score 0 · Answer 3 · answered Mar 10 '12 at 16:33

You could use XStream to serialize your objects in to XML format like:

<tank>
    <id>1</id>
    <speed>12</speed>
    <angMomentum>6</angMomentum>
    <firePower>2</firePower>
    <scanRate>10</scanRate>
</tank>

Its really easy to define how the object should be represented in XML (You can use annotations or methods on the XStream object).

score 0 · Answer 4 · answered Mar 10 '12 at 17:06

The Properties class has everything you need: Using Properties to store configuration values. It handles reading and writing to disk for you, and works as a Map for you to store and retrieve values. No need for serialization, which is extremely brittle in terms of long-term storage, or XML/JSON parsing.

Java Create Configuration-like File

4 Answers4