Java: Best approach to having a long list of variables needed all the time without consuming memory?

Question

I wrote an abstract class to contain all the rules of the application, because I need them almost everywhere in my application. So most of them contain variables static final, something like this:

public abstract class appRules
{
    public static final boolean IS_DEV = true;
    public static final String CLOCK_SHORT_TIME_FORMAT = "something";
    public static final String CLOCK_SHORT_DATE_FORMAT = "something else";
    public static final String CLOCK_FULL_FORMAT = "other thing";
    public static final int USERNAME_MIN = 5;
    public static final int USERNAME_MAX = 16;
    // etc.
}

The class is large and contains LOTS of such variables.

My question is:

• Doesn't set static variables do these variables float in memory all the time?
• You suggest instead of having an abstract class, I have an instance of a class with non-stationary variables (simple public final), so I only instantiate the class and use the variables only when I need them.
• Or what I'm doing is a completely wrong approach, and are you suggesting something else?

Answer 1

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Answer 2

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private static final String CONSTANT_FOO;
private static final String CONSTANT_BAR;
static{
    try{
        Properties props = new Properties();
        InputStream is = 
            MyConstantClass.class
            .getResourceAsStream("my.module.properties");
        props.load(is);

        // you'll actually want to move this to finally, but I'm lazy
        is.close();

        CONSTANT_FOO = props.get("constants.foo");
        CONSTANT_BAR = props.get("constants.bar");

    }catch(Exception e){
        throw new IllegalStateException(e);
    }
}

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Answer 3

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Answer 4

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Answer 5

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Answer 6

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With a minimum wage, you should not spend 1 minute saving 1 MB on a PC or server.