Can we define abstract method in abstract class?

Abstract class: is a restricted class that cannot be used to create objects (to access it, it must be inherited from another class). Abstract method: can only be used in an abstract class, and it does not have a body. The body is provided by the subclass (inherited from).

Is it necessary that all the abstract methods must be defined from an abstract class?

Explanation: It is a rule that if a class have even one abstract method, it must be an abstract class. If this rule was not made, the abstract methods would have got skipped to get defined in some places which are undesirable with the idea of abstract class.

Can abstract methods be defined?

Abstract Classes Compared to Interfaces You cannot instantiate them, and they may contain a mix of methods declared with or without an implementation. However, with abstract classes, you can declare fields that are not static and final, and define public, protected, and private concrete methods.

Is it possible to declare abstract methods as private?

If a method of a class is private, you cannot access it outside the current class, not even from the child classes of it. But, incase of an abstract method, you cannot use it from the same class, you need to override it from subclass and use. Therefore, the abstract method cannot be private.

Is it compulsory for the abstract class to have atleast one method as an abstract?

An abstract class is not required to have an abstract method in it. But any class that has an abstract method in it or that does not provide an implementation for any abstract methods declared in its superclasses or implemented interfaces must be declared as an abstract class.

Can abstract class have only non abstract methods in C#?

You can make use of abstract classes to implement such functionality in C# using the modifier ‘ abstract ‘. An abstract class can contain either abstract methods or non abstract methods. Abstract members do not have any implementation in the abstract class, but the same has to be provided in its derived class.

Can you declare a class as abstract and final?

If you declare a class abstract, to use it, you must extend it and if you declare a class final you cannot extend it, since both contradict with each other you cannot declare a class both abstract and final if you do so a compile time error will be generated.

Can an abstract class define both abstract methods and non-abstract methods?

Yes, we can declare an abstract class with no abstract methods in Java. An abstract class having both abstract methods and non-abstract methods. For an abstract class, we are not able to create an object directly. But Indirectly we can create an object using the subclass object.

Which of the following methods Cannot be declared as private?

We cannot declare abstract methods as private. We cannot declare abstract methods as static. An abstract method can’t be synchronized.

When a class inherits an abstract class and it does not implement all the abstract methods?

Java Abstract Class and Interface

A	If we derive an abstract class and do not implement all the abstract methods, then the derived class should also be marked as abstract using ‘abstract’ keyword
C	A class can be made abstract without any abstract method
D	A class can inherit from multiple abstract classes.

Can we declare abstract method in interface in C#?

An interface will have only abstract methods (method declaration). Interfaces supports Inheritance, Polymorphism (Overloading, Overriding (using the “new” keyword to hide the interface methods above)). We cannot create variables in an interface. Only Properties, Indexers, Methods and Events are allowed in an interface.

Can abstract class have static methods?

No abstract class cannot be static. Abstract class is used to define a general abstraction which then sub-classes inherit to define specialized versions. static keyword in class definition means that all methods in the class are static as well.

When to use an abstract class?

An abstract class can be used when your base class is having some default behaviour and all the classes that extend the base class can use that functionality and on the above they can implement their own business. The disadvantage is the given class can sub class only one class and the scope is narrowed.

What is a public abstract class?

Abstract Class. A class which contains the abstract keyword in its declaration is known as abstract class. Abstract classes may or may not contain abstract methods, i.e., methods without body ( public void get(); ) But, if a class has at least one abstract method, then the class must be declared abstract.

What are abstract classes in Java?

An abstract class in Java is a class that contains one or more abstract methods, which are simply method declarations without a body — that is, without executable code that implements the class or method.