Yes, an abstract class can have a constructor in Java. You can either explicitly provide a constructor to abstract class or if you don't, the compiler will add default constructor of no argument in abstract class. In order to use an abstract class in Java, You need to extend it and provide a concrete class..
Also to know is, can we have parameterized constructor in abstract class?
Yes, an abstract class can have a parameterized constructor. This will then be used by the subclasses that extend the abstract class. Originally posted by Marilyn deQueiroz: Yes, an abstract class can have a parameterized constructor.
Secondly, how do you find the abstract class of a constructor? You can define a constructor in an abstract class, but you can't construct that object. However, concrete sub-classes can (and must) call one of the constructors defined in the abstract parent class. You can't call an abstract class constructor with a class instance creation expression, i.e.
Also asked, why does an abstract class have a constructor?
A constructor in Java doesn't actually "build" the object, it is used to initialize fields. Imagine that your abstract class has fields x and y, and that you always want them to be initialized in a certain way, no matter what actual concrete subclass is eventually created.
Can an interface have a constructor?
This is a most frequently asked java interview question. The answer is No, interface cannot have constructors. In order to call any method we need an object since there is no need to have object of interface, there is no need of having constructor in interface (Constructor is being called during creation of object).
Related Question Answers
Can constructor be static?
Constructor is NON-STATIC and it cannot be declared as static in java . Instance is created by 'new' operator and that need not to be initialized to call a constructor (as constructor initializes the object). A constructor is never called as object. constructor() like methods.Can a constructor be abstract?
You can't have an abstract constructor, as abstract means you need to provide the implementation for that at some point of time in your subclass. But you cannot override constructor. There will be no point in having an abstract constructor : You will always call the constructor of child class and not of base class.Can abstract class have normal methods?
It can have abstract methods(methods without body) as well as concrete methods (regular methods with body). A normal class(non-abstract class) cannot have abstract methods. An abstract class can not be instantiated, which means you are not allowed to create an object of it.Can abstract class have private variables?
Abstract classes can have private methods. Abstract classes can have instance variables (these are inherited by child classes). Interfaces can't. Finally, a concrete class can only extend one class (abstract or otherwise).Can an abstract class be final?
An abstract class is incomplete and can only be instantiated by extending a concrete class and implementing all abstract methods, while a final class is considered as complete and cannot be extended further. In short, the use of keywords abstract and final together is illegal in Java.Can we override static method?
Answer is, No, you can not override static method in Java, though you can declare method with same signature in sub class. It won't be overridden in exact sense, instead that is called method hiding. As per Java coding convention, static methods should be accessed by class name rather than object.Can abstract class have static methods?
Yes, abstract class can have Static Methods. The reason for this is Static methods do not work on the instance of the class, they are directly associated with the class itself.Can abstract class have variables?
An abstract class may contain non-final variables. Type of variables: Abstract class can have final, non-final, static and non-static variables. Interface has only static and final variables. A Java abstract class can have class members like private, protected, etc.Can a constructor be final?
No, a constructor can't be made final. A final method cannot be overridden by any subclasses. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors. Therefore, java does not allow final keyword before a constructor.Can an abstract class have a final method?
Yes, there may be "final" methods in "abstract" class. But, any "abstract" method in the class can't be declared final. It will give "illegal combination of modifiers: abstract and final" error. Here is the working example of the implementation.Can we create an instance of an abstract class?
No, you cannot create an instance of an abstract class because it does not have a complete implementation. The purpose of an abstract class is to function as a base for subclasses. It acts like a template, or an empty or partially empty structure, you should extend it and build on it before you can use it.Can abstract class have public constructor?
Are there good reasons for a public constructor of an abstract class. It is not possible to create an object by directly calling the constructor of an abstract class. The constructor of an abstract class can be called only from a derived class. Yet Java allows the constructor of an abstract class to be public .What is the difference between abstract class and interface?
Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior. Variables declared in a Java interface is by default final. An abstract class may contain non-final variables.Can an abstract class extend another abstract class?
Abstract classes can implement one or more interfaces and can extend one abstract class at most. A class can be an abstract class without having any methods inside it. But if it has any methods inside it, it must have at least one abstract method. This rule does not apply to static methods.Can an abstract class have a constructor C#?
Answer: Yes, an abstract class can have a constructor, even though abstract class cannot be instantiated. An abstract class constructor c# code example will be explained. For example in program, if we create object of derived class then abstract base class constructor will also be called.What is purpose of abstract class?
A Java abstract class is a class which cannot be instantiated, meaning you cannot create new instances of an abstract class. The purpose of an abstract class is to function as a base for subclasses. This Java abstract class tutorial explains how abstract classes are created in Java, what rules apply to them.What is abstract class in OOP?
An abstract class is a template definition of methods and variables of a class (category of objects) that contains one or more abstracted methods. Abstract classes are used in all object-oriented programming (OOP) languages, including Java (see Java abstract class), C++, C# and VB.NET.What is the use of abstract class?
abstract keyword is used to create a abstract class and method. Abstract class in java can't be instantiated. An abstract class is mostly used to provide a base for subclasses to extend and implement the abstract methods and override or use the implemented methods in abstract class.What is an interface?
In computing, an interface is a shared boundary across which two or more separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these. 
