Doubt with static initializers

[vinayak manda]

public class Test {
static {int a=5;}
public static void main(String args[]{
System.out.println(a);
}
}

Is this legal,is it true that a variable declared in a static initializer is not accessible outside the enclosing block.

[Chris Allen]

Originally posted by vinayak manda:
public class Test {
static {int a=5;}
public static void main(String args[]{
System.out.println(a);
}
}

Is this legal,is it true that a variable declared in a static initializer is not accessible outside the enclosing block.

Extend this concept beyond a static variable to any variable that is declared within the curly braces. The curly braces provide the scoping context for the variable lifetime. It really doesn't matter if it is a static variable or not. For example, if I add a bit more code to your example:

  public static void main(String args[]) {
    System.out.println(a); 
    { int b=1;}
    System.out.println(b); 
  }

I will get the same error as I did for a.

[Rovas Kram]

It really doesn't matter if it is a static variable or not.

But what does static {int i=0} mean?

[vinayak manda]

It is way of initialising the static variables in a method block.And where i as defined in the block is one copy per class (NOT ONE PER OBJECT)

[Ilja Preuss]

In your example, a is *not* a static field, but a *local* variable of the static initializer.

A static initializer is simply a block of code that will be executed when the class is loaded.

[vinayak manda]

You mean that I can declare both local variables and static variables in static initializers.
I shouldn't be declaring instance variables in it ,right?.
As class is loaded,static block will execute ,it will initialize the variables to thier defautls when not initialized expicitly.

Correct me If I'am wrong.

[Ernest Friedman-Hill]

Any variables declared in a static initializer will be local to that block. You can initialize -- assign a value to -- a static variable in such a block, but it must be declared at class scope.

[Stefan Wagner]

public class Test
{
static int b;
static int c;
int d;
 
static
{
int a=5; // senseless - never used, unknown outside
 
b = Foo.getSize (); /* Foo.getSize needs to be static too! */
if (b < 17) c = b*2;
else c = b*3;
// d = 10; // not allowed - nonstatic variable
}
 
public Test ()
{
System.out.println (b + c);
}
}

Perhaps this is more clear to you.
b and c are declared outside the static initializer.
You need a static block only to use conditionals (if, while, for, ...).
static b = Foo.getSize (); might be declared and initialized without a static block.

[Ilja Preuss]

Originally posted by Stefan Wagner:
You need a static block only to use conditionals (if, while, for, ...).

They are also often used to initialize collections:

static final Map colorsByName = new HashMap();
static {
  colorsByName.put("black", Color.BLACK);
  ...
}