Java static code block

Question

Recently in a lot of programs I've been looking at, I've noticed

static {
    //some code here
}

I'm just looking for some information about this particularly, I'm used to blocks of code all being in methods, or simply classes, does this simply set all code within the block with a static modifier, or is there something more to it?

I guess you can consider it to be like a constructor, but for the class, not any instances of the class. Although I assume you can have multiple static blocks, but of course only one constructor per class. — Alexander Mills, Jun 23 '15 at 08:34

score 15 · Accepted Answer · edited May 23 '17 at 11:54

15

This might be a duplicate question from Static Initialization Blocks

The static block only gets called once, no matter how many objects of that type you create.

edited May 23 '17 at 11:54

Community

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answered Nov 10 '12 at 05:42

Ahmad

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Does JVM guarantee that the static block will be executed only once per application domain ? – AlexVPerl Apr 18 '15 at 20:42
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The static block gets called each time the class is loaded. If there are multiple classloaders that load the class, the code gets executed multiple times. – Gijs Overvliet May 22 '15 at 10:06
if the program starts multiple times, the static block gets called multiple times also – Alexander Mills Jun 23 '15 at 08:32
Is it a possibility that the class never gets loaded and hence the method never gets called? – LearningToCode Mar 24 '17 at 16:49

score 4 · Answer 2 · answered Nov 10 '12 at 05:41

4

The code inside a static block is executed first (e.g. before your constructor) once the JVM loads your class.

answered Nov 10 '12 at 05:41

Juvanis

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Would this code be inaccessible from external classes? – Dan Nov 10 '12 at 05:42
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Here is the official explanation from Oracle http://docs.oracle.com/javase/tutorial/java/javaOO/initial.html – Jason Sperske Nov 10 '12 at 05:43

score 1 · Answer 3 · answered Nov 10 '12 at 05:43

1

Static blocks get called once (at a class level) and does not belong to a specific instance.

you can find more info (with good examples) here, or in the official oracle documentation.

answered Nov 10 '12 at 05:43

Ofir Farchy

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Java static code block

3 Answers3