private constructor in abstract classes

[Minal Silimkar-Urankar]

I tried to create private constructor in abstract classes.
It is allowing.

What is the use of private condtructors in absract claases?

[Kishore Kumar]

abstract class can have a private constructor. But that class cannot be extended by another class. Instead add a static inner class inside the abstact class and extend that abstract class.

 abstract class  Base{
public abstract void set();
 
private Base(){
System.out.println("Private Constructor!");
}
static class Derived extends Base{
public void set(){
System.out.println("set() method implemented!");
}
}
public static void main(String[] args){
new Base.Derived().set();
}
}   

This is a small sample code.

[Minal Silimkar-Urankar]

Ok.

I got how I can use abstract class with private constructor.
Where we will use this type of constructors?