constructor vs overridable method

[pepe34]

Hi,

I have a question about overridable method call in constructor.

For example:

class A {
public A() {
fun();
prv_fun();
}
public void fun() {
System.out.println("A");
}
private void prv_fun() {
System.out.println("PRV A");
}
}

public class B extends A {
public B() {
fun();
}
public void fun() {
System.out.println("B");
}
public static void main(String[] args) {
B obj = new B();
}
}

the result is:

B
PRV_A
B

Why does the constructor of class A invoke class B fun() method and class A prv_fun() private method ?

Constructor A bytecode:
public <init>()V
L0
LINENUMBER 2 L0
ALOAD 0
INVOKESPECIAL java/lang/Object.<init>()V
L1
LINENUMBER 3 L1
ALOAD 0
INVOKEVIRTUAL A.fun()V
L2
LINENUMBER 4 L2
ALOAD 0
INVOKESPECIAL A.prv_fun()V
L3
LINENUMBER 5 L3
RETURN
L4
LOCALVARIABLE this LA; L0 L4 0
MAXSTACK = 1
MAXLOCALS = 1

and it contains command INVOKEVIRTUAL A.fun()V,
so why does the constructor of class A invoke B.fun() ?

Thanks

[Fubarable]

so why does the constructor of class A invoke B.fun() ?

It's being called inside of a B object, and the magic of polymorphism allows it to call B's method. This is one reason it is potentially dangerous to call overridable methods inside of a class's constructor.

[pepe34]

Ok, but why the bytecode contains "INVOKEVIRTUAL A.fun()V" ?

I wonder if dynamic linking works here.