Is a Java static block equivalent to a C# static constructor?

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+3 Q:

Is a Java static block equivalent to a C# static constructor?

What is the real difference between a C# static constructor and a Java static block?

They both must be parameterless. They are both called only once, when the related class is first used.

Am I missing something, or are they the same thing, just with different names?

+4 A:

They are equivalent, except that a C# class can only have one static constructor (plus static field initializers).

Also, in C#, a static constructor will apply the beforefieldinit flag.

SLaks 2010-03-17 19:35:03

Obviously Java is not going to apply any beforefieldinit flags, as it isn't compiled to MSIL.

Joren 2010-03-17 19:38:27

@Joren: I realize that. However, it is a difference in the behavior of the two features.

SLaks 2010-03-17 19:39:41

Yes, but my (not so explicit, I admit) point was: It might be more useful to explain the difference in terms of the code semantics (i.e. order of field initialization and the static constructor) than in terms of implementation details. (Especially when it's details that don't even have any meaning for one of the two languages being considered.)

Joren 2010-03-17 19:43:51

Would you both agree that if one was converting Java code to C#, that there would exist no risk of losing functionality?

Mackenzie 2010-03-17 19:44:56

@Mackenzie: As long as the code doesn't have side effects that must be run lazily (or not), it should be equivalent.

SLaks 2010-03-17 19:48:17

Mackenzie 2010-03-17 19:52:25

I thought java static blocks were executed when the class was loaded, not at the first use of the class (via a constructor or static method call). That's a subtle point since (iirc) classloaders will usually load all referenced classes at startup (so the static blocks will be executed immediately) but you can always load a class manually later. I have no idea how C# handles this.

bgiles 2010-03-17 20:41:08

d'oh - a few hours after making that last comment I was skimming through "Effective Java, 2E" and came across that very issue. Java static blocks are only executed when the class is first used, not first loaded if they do any pre-loading.

bgiles 2010-03-19 21:38:46

They are not.

In C#, there blocks can only hold constructors. In java you are able to execute statements.

2010-07-21 20:26:55

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Is a Java static block equivalent to a C# static constructor?

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