A New Learner Stuck in one problem

Question

Hi,
I ahve just started leaning JAVA. I have written one code but getting some error. Can any body help me out in debugging and explaing the cause of the error:
Thanks in advance,
Rhushi.
The error is pasted after the code.
Code:
class SetEmployee {
     int empno;
     SetDate dob;
     String name;
     static int count;
     static {        
          count=0;
     public SetEmployee()
          ; //this(name,dob=new SetDate(),empno);
     public SetEmployee(String n, SetDate d,int en)
          empno=en;
          dob=d;
          name=n;
          count++;
     public String toString(){
          return ("\nSerial No : "+ count +"\n Name of the Employee : "+ name +"\n His Employee Number is : "+ empno +"\n And his date of Birth is : "+ dob);
public class Employee {
     public static void main(String[] args){
          SetEmployee e1=new SetEmployee("Rhushi",(new SetDate(28,11,1980)),746);
          System.out.println("The information of the Employee is "+ e1 +"\n");
Error:
//The following error comes if we uncomment the line 12 otherwise the prog run as expected.
/*Employee.java:12: cannot reference name before supertype constructor has been called
this(name,dob=new SetDate(),empno);
^
Employee.java:12: cannot reference dob before supertype constructor has been called
this(name,dob=new SetDate(),empno);
^
Employee.java:12: cannot reference empno before supertype constructor has been called
this(name,dob=new SetDate(),empno);*/
^

Answer 1

/*Employee.java:12: cannot reference name before supertype constructor has been called
this(name,dob=new SetDate(),empno);
Employee.java:12: cannot reference dob before supertype constructor has been called
this(name,dob=new SetDate(),empno);
Employee.java:12: cannot reference empno before supertype constructor has been called
this(name,dob=new SetDate(),empno);*/Every class inherits (implicitly) from the Object class. Every class is constructed like an onion,
from the inside out, layer after layer. First the super class object is constructed (the inner layer)
and finally the current object is constructed.
A constructor can have two types of first statements --
1) and explicit call to this( ... ), i.e. another constructor or
2) a call to super( ...), i.e. a call to a super constructor.
If you don't explicitly supply 1) or 2), the compiler supplies a call super(); as the first statement
of the constructor.
You supplied a call to this( ... ) in your constructor. The compiler 'knows' then that a call to
any super constructor hasn't been called at that point, but you supply those member fields of
the current class as parameters to the other constructor. The inner layer hasn't been constructed
yet, so the outer layer (where those member fields reside) doesn't even exist yet; hence the
compiler diagnostics.
If member fields are not implicitly initialized, they take a value '\0', 0, 0.0 or null, whichever value
is appropriate for the type of the field. you could change your offending ctor to -- this(null, new SetDate(), 0); This has the same effect, by you're not referencing the (not yet existing) member variables anymore.
kind regards,
Jos