Abstract class can have concerete and abstract methods. The abstract class can have public, private, protected or default variables and also constants. … However, in the case of an abstract class, the method can be simply implemented in the abstract class and the same can be called by its subclass.
Can we use protected in abstract class?
Yes, you can declare an abstract method protected. If you do so you can access it from the classes in the same package or from its subclasses.
Can an abstract class have private variables?
Abstract classes can have private methods. Interfaces can’t. Abstract classes can have instance variables (these are inherited by child classes). Interfaces can’t.
Why variables Cannot be abstract?
Abstract implies that the abstract methods within abstract classes must be coded. A variable cannot be coded because it is a primitive or reference that can only be assigned a value.
Who can access protected variables?
Protected Access Modifier – Protected
Variables, methods, and constructors, which are declared protected in a superclass can be accessed only by the subclasses in other package or any class within the package of the protected members’ class. The protected access modifier cannot be applied to class and interfaces.
Can abstract class have fields?
An abstract class may have static fields and static methods. You can use these static members with a class reference (for example, AbstractClass.
Can abstract class have constructor?
The constructor inside the abstract class can only be called during constructor chaining i.e. when we create an instance of sub-classes. This is also one of the reasons abstract class can have a constructor.
Can abstract class have static methods?
Yes, of course you can define the static method in abstract class. you can call that static method by using abstract class,or by using child class who extends the abstract class. Also you can able to call static method through child class instance/object.
Can constructor be private?
Yes. Class can have private constructor. Even abstract class can have private constructor. By making constructor private, we prevent the class from being instantiated as well as subclassing of that class.
What is difference between abstract class and interface?
Abstract class and interface both can’t be instantiated. But there are many differences between abstract class and interface that are given below.
Difference between abstract class and interface.
|3) Abstract class can have final, non-final, static and non-static variables.||Interface has only static and final variables.|
Can we declare variables as abstract?
No. You can only declare classes as abstract, and variables as references to classes (or as value types). And base can hold a reference to any class derived from MyBase.
What is the use of an abstract variable?
abstract is a non-access modifier in java applicable for classes, methods but not variables. It is used to achieve abstraction which is one of the pillar of Object Oriented Programming(OOP). Following are different contexts where abstract can be used in Java.
Can an abstract class be inherited?
An abstract class cannot be inherited by structures. It can contains constructors or destructors. It can implement functions with non-Abstract methods.