Call super class method automatically

Question

Consider the following class

class A{
    public void init(){
        //do this first;
    }
    public void atEnd(){
        //do this after init of base cl         


        

Answer 1

One way to do this is by making init() final and delegating its operation to a second, overridable, method:

abstract class A {
  public final void init() {
    // insert prologue here
    initImpl();
    // insert epilogue here
  }
  protected abstract void initImpl();
}

class B extends A {
  protected void initImpl() {
    // ...
  }
}

Whenever anyone calls init(), the prologue and epilogue are executed automatically, and the derived classes don't have to do a thing.