Why can't we set the value of static final variable in static block through class name [duplicate]

Question

For example, consider code snap below:

public static final int a; public static final int b;  static {     a = 8;       // it's working     Test.b = 10; // compilation error Test.b cannot be assigned.  } 

Why can't we use Test.b = 10; inside a static block of the Test class itself? Without the class name it's working fine.

Is there any reason behind this?

Answer 1

A static final variable must be initialized before use. It may be initialized either directly at declaration time, or in a static block.

But when you use class.var = x it is not seen as an initialization but as an assignation.

With a JDK 7, the error is cannot assign a value to final variable.

That explains why it works if you remove the final keyword

class Test {      static final int a = 2; // initialization at declaration time     static final int b;     static final int c;      static {         b = 4;  // initialization in static block         Test.c = 6; // error : cannot assign a value to final variable c     }     ...  } 

EDIT

In the JLS the correct word for initialization is definite assignement

Extract from the JLS :

For every access of a local variable or blank final field x, x must be definitely assigned before the access, or a compile-time error occurs.

Similarly, every blank final variable must be assigned at most once; it must be definitely unassigned when an assignment to it occurs.

Such an assignment is defined to occur if and only if either the simple name of the variable (or, for a field, its simple name qualified by this) occurs on the left hand side of an assignment operator.

For every assignment to a blank final variable, the variable must be definitely unassigned before the assignment, or a compile-time error occurs.

emphasize mine, but I think this is the real reason for the error.