Class usage inside class static initialization block

Question

Probably it is discussed somewhere but I failed to find it.

I need to load class properties (java.util.Properties) inside class static initialization block. This is to make possible to access some class general options even without its objects creation. To do so I need appropriate Class object. But of course access to such Class object fails on null object. Something like this.

Class Name {

    private static Properties properties;

    static {
        Name.properties = new Properties();
        Name.properties.load(Name.class.getResourceAsStream("Name.properties"));
    }

}

Any idea how to handle this situation?

UPDATE:
It was resource name (should be "/Name.properties" for my case). Everything else was OK. +1 for all meaningful answers from me and ... don't forget to check operations one by one :-).

Thank you, it was actually done in original code, typo. Corrected. — Roman Nikitchenko, Nov 06 '13 at 11:37
I hope following will help you: http://stackoverflow.com/questions/1044855/load-java-properties-inside-static-intializer-block — Imran, Nov 06 '13 at 11:37
If you're setting Name.properties to a new Properties object, the only thing that could be null is the value returned by `getResourceAsStream`. Make sure Name.properties is in the same directory as Name.class in your .jar file. — VGR, Nov 06 '13 at 11:45
This code looks like you want to make the `properties` field `final` too. — Holger, Nov 06 '13 at 13:38

score 3 · Accepted Answer · answered Nov 06 '13 at 11:36

3

properties field must be static. And before load you need to initialize static variable with proeprties = new Properties() after that you can invoke load

answered Nov 06 '13 at 11:36

Areo

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Abdullah Shaikh · Answer 2 · 2013-11-06T12:06:43.880

1

Declare properties as static and initialize

static Properties properties;

or

static Properties properties = new Properties();

and static block should be

static {
    try {
        properties = new Properties(); //if you have not initialize it already
        Name.properties.load(Name.class.getResourceAsStream("Name.properties"));
    } catch (IOException e) {
        throw new ExceptionInInitializerError(e); //or some message in constructor
    }
}

You need to catch IOException while loading properties file

edited Nov 06 '13 at 12:06

answered Nov 06 '13 at 11:37

Abdullah Shaikh

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2

`printStackTrace` is one of the worst ways to handle the exception, unless Roman actually doesn't care if the properties file was loaded. The correct course of action is `throw new RuntimeException(e);`. – VGR Nov 06 '13 at 11:43
I know its just that I wanted to be specific to question, the OP needs to handle exceptions properly. I won't be writing entire code for him :) – Abdullah Shaikh Nov 06 '13 at 11:45
1

An `ExceptionInInitializerError` would be even better IMHO: "Signals that an unexpected exception has occurred in a static initializer. An ExceptionInInitializerError is thrown to indicate that an exception occurred during evaluation of a static initializer or the initializer for a static variable." – Gyro Gearless Nov 06 '13 at 11:48
@GyroGearless yes ExceptionInInitializerError would be more appropriate – Abdullah Shaikh Nov 06 '13 at 12:04

score 0 · Answer 3 · answered Nov 06 '13 at 12:02

Final code based on all suggestions is like this:

Class Name {

    private static final Properties properties = new Properties();

    static {
        try {
            InputStream stream = Name.class.getResourceAsStream("/Name.properties");
            if (stream == null) {
                throw new ExceptionInInitializerError("Failed to open properties stream.");
            }
            Name.properties.load(stream);
        } catch (IOException e) {
            throw new ExceptionInInitializerError("Failed to load properties.");
        }
    }
}

Class usage inside class static initialization block

3 Answers3