default values of reference in java

class defaultref
{
double p,q;
defaultdemo defdemmo;
public static void main(String args[])
{
defaultref ref= new defaultref();
System.out.println("p :"+ref.p);
System.out.println("q :"+ref.q);
System.out.println("s :"+ref.defdemmo);

System.out.println("byte :"+ref.defdemmo.b);
System.out.println("short :"+ref.defdemmo.s);
System.out.println("long :"+ref.defdemmo.l);
System.out.println("int :"+ref.defdemmo.i);
System.out.println("float :"+ref.defdemmo.f);
System.out.println("double :"+ref.defdemmo.d);
System.out.println("char :"+ref.defdemmo.ch);
System.out.println("boolean:"+ref.defdemmo.bl);
}
}
======================================================
output :

p :0
q :0
s :null

And for others null pointer exception will show