What is use of abstact class constructor ?

Question

Use of abstract class constructors when object creation is not supported for abstract class?

Answer 1

But it can be used as a reference for the instance of the concrete class which is extending that abstract class and providing implementation for all abstract methods.

You can call the constructor of abstract class through the class extending it using super method.

Answer 2

You can initialize shared attributes of childs simply by calling parent constructor: super(a, b, ...)