What is difference to extend abstract class and non abstract class?

Question

What is difference between abstract class and non abstract class when extending derived classes? Both class I didn't use the method overriding and abstract methods (i.e. abstract class). Just I inherited the properties. What and why did prefer the class?

Ex:

Code 1:

abstract class a {  
    protected int empnno; 
    protected String empname; 
} 

class b extends a { 
    ...
}

Code 2:

class a {  
    protected int empnno; 
    protected String empname; 
}

class b extends a { 
    ...
}

Answer 1

what is difference to extend abstract class and non abstract class?

Abstract classes may have abstract methods. Abstract methods are methods without implementations and these must be implemented by your subclass (unless you make your subclass abstract too).

Since your a class have no abstract methods, there is no difference what so ever from a subclass-perspective. (The only difference is that if a is abstract it may no longer be instantiated as is. It may only be instantiated in terms of subclasses.)