Constructor chains and trace traps

Tracing a constructor chain — the exam's favorite:

public class A {
    public A() { System.out.print("A"); }
}

public class B extends A {
    public B() { System.out.print("B"); }   // implicit super() first
}

new B() prints AB: the superclass part is always built first. With explicit super(args) and fields, the order is: super constructor → subclass field initializers → subclass constructor body.

What subclasses don't inherit: private fields (exist but hidden), constructors (called, not inherited), static methods are hidden not overridden (out of scope here).

Common trace traps: calling an overridden method from inside the superclass constructor runs the subclass version before subclass fields are initialized — a classic "why is my field null" puzzle. The exam uses this only in the hardest trace items; know the mechanism, don't memorize beyond it.