Vxyz eom

Matthew Brown wrote:Here's what's going on...

You aren't specifying a constructor for the B class. So the compiler inserts a default constructor, taking no arguments.

Because B is a subclass of A, any constructor of B must call a constructor of A. Again, if you omit this, the compiler will insert the call for you. But it can only insert a no-arg constructor like this. In the second case, there isn't a no-arg constructor. So if you want to inherit from B in that case you need to put in the constructor calls explicitly. For instance, like this:

class A { A(int b) { printf("Hello ! I am A"+i); } } class B extends A { B(int b) { super(b); } public static void main(String args[]) { A a=new A(5); } }

Actually, writing that I've realised there were two problems. Your examples didn't have any constructors. They were ordinary methods - constructors don't have a return type.

Thanks Matthew You are Correct.

vibhor sharma wrote:I doubt even first one works well ..

void A() { printf("Hello ! I am A"); }
It is not a constructor , eventually a valid java method which happens to be a same name as a class name .... remember constructors doesn't have return type, not even void .

PS : In my opinion constructors cant be inherited , be it default one ...

Now is it correct Vibhor ???

mrkamal joshi wrote:byte a=100;// works fine
//but
byte b=a+a;//don't why??

See This..
Compiled from "A.java" class A extends java.lang.Object SourceFile: "A.java" minor version: 0 major version: 50 Constant pool: const #1 = Method #3.#12; // java/lang/Object."<init>":()V const #2 = class #13; // A const #3 = class #14; // java/lang/Object const #4 = Asciz <init>; const #5 = Asciz ()V; const #6 = Asciz Code; const #7 = Asciz LineNumberTable; const #8 = Asciz main; const #9 = Asciz ([Ljava/lang/String;)V; const #10 = Asciz SourceFile; const #11 = Asciz A.java; const #12 = NameAndType #4:#5;// "<init>":()V const #13 = Asciz A; const #14 = Asciz java/lang/Object; { A(); Code: Stack=1, Locals=1, Args_size=1 0: aload_0 1: invokespecial #1; //Method java/lang/Object."<init>":()V 4: return LineNumberTable: line 1: 0 public static void main(java.lang.String[]); Code: Stack=1, Locals=2, Args_size=1 0: bipush 100 2: istore_1 3: return LineNumberTable: line 5: 0 line 8: 3 } :rolling:

Hello Folks !
I have a problem and doubts with constructors.
does any one tell me why constructor with parameters cannot be inherit ???remember the fact that default constructor can inherit.
class A { void A() { System.out.println("Hello ! I am A"); } } class B extends A { public static void main(String args[]) { A a=new A(); } }
this works well.
But class A { void A(int b) { System.out.println("Hello ! I am A"+i); } } class B extends A { public static void main(String args[]) { A a=new A(5); } } Not Working Explain with Details ....!!!