What's the point in having an abstract class with no abstract methods?

Question

Can have an abstract class implementing all of its methods-- with no abstract methods in it.

Eg.:

public abstract class someClass          


        

Answer 1

We generally use Abstraction concept with inheritance

Consider using abstract classes if any of these statements apply to your situation:

• You want to share code among several closely related classes.

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To answer your question,

Why declare a class with concrete methods Abstract?

One possible reason is to support inheritance without actually creating objects

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Assume you have two classes one Abstract and other Concrete

Abstract class : AbsClass

abstract class AbsClass {
  int a = 5;

  //Constructor
  public AbsClass() {
    System.out.println(a);
  }

  void methodA() {
    System.out.println(a + 10);

  }

}

and Concrete class : ConcreteClass

class ConcreteClass {
  int a = 10;

 //Made the constructor Private to prevent from creating objects of this class
  private ConcreteClass() {
    System.out.println(a);

  }

  void methodA() {
    System.out.println(a + 10);
  }

}

The above two classes should function similarly (?) Until you try to Subclass them

class AbsImplementer extends AbsClass {
//Works fine

}

class ConcImplementer extends ConcreteClass {
//Compilation Error Implicit super constructor ConcreteClass() is not visible


}