java - Is there a difference between initializing a variable with its declaration, or in a static initialization? -

the static initializer called once classloader, want, doing initialization outside static code block more readable (debatable). there difference between two?

private static final map<myenum, cheese> cheesecache;      static {         parsercache = new enummap< myenum, string>(myenum.class){{             for(myenum myenum: myenum.values()){                 put(myenum, new cheese(myenum)) ;             }          }};     } 

or :

private static final map<lab, labresultparser> cheesecache          = new enummap< myenum, string>(myenum.class){{             for(myenum myenum: myenum.values()){                 put(myenum, new cheese(myenum)) ;             }         }}; 

it can affect ordering - example have:

private static final int declaredfirst;  private static final int declaredsecond = new random.nextint();  static {     declaredfirst = declaredsecond + 1; } 

the initializers executed in textual order. of course, have declared declaredfirst second:

private static final int declaredsecond = new random.nextint(); private static final int declaredfirst = declaredsecond + 1; 

personally use static initialization blocks can't cleanly express initial value in single expression.

oh, , if initialize in static initialization block, variable can't treated constant expression:

private static final int this_is_a_constant = 10; private static final int thisisnotaconstant;  static {     thisisnotaconstant = 20; }  public static void main(string[] args) {     system.out.println(this_is_a_constant); // 10 inlined     system.out.println(thisisnotaconstant); // 20 not inlined } 

that's relevant, of course.

so in most cases it's personal choice. of course in case, ability use more statements means don't need use ugly (imo) "anonymous inner class initialization":

private static final map<myenum, cheese> cheesecache;  static {     parsercache = new enummap<>(myenum.class);     (myenum myenum: myenum.values()) {         put(myenum, new cheese(myenum));     } }