Any way to _not_ call superclass constructor in Java?

Question

If I have a class:

class A {
   public A() { }
}

and another

class B extends A {
   public B() { }
}

is t

Answer 1

The closest you can achieve to the desired behaviour is to delegate initialisation normally performed in the constructor to a template method, which you then override in your subclass implementation. For example:

public class A {
  protected Writer writer;

  public A() {
    init();
  }

  protected void init() {
    writer = new FileWriter(new File("foo.txt"));
  }
}

public class B extends A {
  protected void init() {
    writer = new PaperbackWriter();
  }
}

However, as other people have noted this can typically indicate a problem with your design and I typically prefer the composition approach in this scenario; for example in the above code you could define the constructor to accept a Writer implementation as a parameter.