Question

Why in the below code is assigning a value to the static variable acceptable but using that same variable is not?

class Test
{
static
{
   var=2;  //There is no error in this line
   System.out.println(var); //Why is there an error on this line if no error on the above     line
}
static int var;
}

Answer 1

Because the usage is not on the left hand side of an assignment, as explained below:

From section 8.3.2.3 of the JLS, Restrictions on the use of Fields during Initialization:

The declaration of a member needs to appear before it is used only if
the member is an instance (respectively static) field of a class or
interface C and all of the following conditions hold:

• The usage occurs in an instance (respectively static) variable
  initializer of C or in an instance (respectively static) initializer
  of C.

• The usage is not on the left hand side of an assignment.

• C is the innermost class or interface enclosing the usage.

A compile-time error occurs if any of the three requirements above are
not met.