initialization

[saravanan ragunathan]

class Ex
{ 
int a;
int b;
 Ex(){
   a=5;
  }
}

class ExTest
{
   public static void main(String[] args)
  {
        Ex obj=new Ex();
        System.out.println("b = "+obj.b);
  }
}

output: b = 0

i heard that when we don't specify the constructor
compiler creates the default constructor which intializes
instance variables ...but in this example i created the constructor
and initialized variable a and i didn't initialize variable b..
when i invoke obj.b ..it gives 0 (default value) ..
so where b gets initialized....

[Stephan van Hulst]

Static and member variables are always initialized to 0, null, false, etc. before any constructors are executed.

[Campbell Ritchie]

saravanan ragunathan wrote: . . . compiler creates the default constructor which intializes instance variables . . .

Whoever told you that was mistaken. The default constructor does nothing at all. As Stephan van Hulst said, that leaves the default values unchanged.

[saravanan ragunathan]

Stephan van Hulst wrote:Static and member variables are always initialized to 0, null, false, etc. before any constructors are executed.

where these variables gets initialized to default values..using default constructor?

[Stephan van Hulst]

No. When you declare a static or member variable, it will have this form:

<Type> <Name> = <Value>.

The value is assigned to the variable before any constructor or initializer is ran.
If you don't supply the = <Value> part, the compiler will more or less add it for you, setting the variable to 0, null, false, etc.

[Campbell Ritchie]

saravanan ragunathan wrote: . . . where these variables gets initialized to default values..using default constructor?

Did you read my earlier posting?

[Joanne Neal]

Campbell Ritchie wrote:The default constructor does nothing at all.

<pedantic>
It calls its parent's no arg constructor
</pedantic>

[Campbell Ritchie]

I take your point, Joanne, but to be pedantic on my part it's a superclass not parent

[Joanne Neal]

Campbell Ritchie wrote:I take your point, Joanne, but to be pedantic on my part it's a superclass not parent

Fair enough. We'll call it a draw this time

[Campbell Ritchie]

I'll be happy with a draw; I usually lose to you