0
In two situations:
- You want the child class to provide certain behavior while making sure that certain other behavior is as you want it (Through the concrete methods that you create)
- You dont want any other class to be able to instantiate your class
Wiki User
∙ 13y ago
Add your answer:
Earn +20 pts
Abstract class can be private?
A class can either be default or public it can never be declared as private, so the question of abstract class at the file level does not arise. But an inner class can be declared private and abstract as well.
When do you declare a method or class abstract in java?
when overriding of a class or a method is necessary, they can be declared as abstract
What happens if an abstract modifier is applied to class. Explain?
The classes which have one or more abstract methods are abstract. To declare a class as abstract, use the abstract keyword in front of the class keyword, before the class declaration. Abstract classes cannot be instantiated. Similarly the new keyword cannot be used to create an object of the abstract class. Remember that the constructors and static variables cannot be declared as abstract. Any subclass of an abstract class must either implement all of the abstract methods in the superclass or be itself declared abstract.
Can abstract method be overriden?
An overridden method is one which has already been implemented in the parent class with the same signature but has again been coded in the current class for functionality requirements. An abstract method is one which has only been declared in a class and would have to be implemented by the class that extends this abstract class. The implementation for the method is not available in the class in which it is declared.
When an interface method is implemented in a class it must be declared as?
Abstract type
When an abstract modifier applied to a class?
An Abstract class is a special kind of class that cannot be instantiated. It has one or more methods which are not implemented in the class. These methods are declared abstract and they do not contain any code inside them. Ex: abstract class Parent { public abstract String getSon(); public abstract String getDaughter(); .... .... //More methods that contain specific behaviour/code in them } The above is an abstract class "Parent" that has a lot of functionality but it has declared two abstract methods which have no code inside them. Any class that has one or more abstract methods has to be abstract. This abstract class cannot be instantiated. i.e., the below piece of code will not work. The code will not even compile. Parent object = new Parent();
Abstract method with example in java?
An abstract in java is used to specify that the class/function is not yet complete. When a class in declared as abstract it means that it is not meant to be instantiated (you can't create variables of that type). This is because they are meant to be more of a guideline for other classes. When a class extends an abstract class it must either define all of the abstract methods from the abstract class or it must also be declared as an abstract class itself.
What is the difference between abstract class and normal class?
Any class which has one or more abstract methods is called an abstract class. But in the normal class we can't have any abstract methods. We cannot create an object for the abstract classes. When we inherit the abstract class we should implement the abstract method which we inherit.
What are abstract classin java?
An Abstract class is a special kind of class that cannot be instantiated. It has one or more methods which are not implemented in the class. These methods are declared abstract and they do not contain any code inside them.Ex:abstract class Parent {public abstract String getSon();public abstract String getDaughter();........//More methods that contain specific behaviour/code in them}The above is an abstract class "Parent" that has a lot of functionality but it has declared two abstract methods which have no code inside them. Any class that has one or more abstract methods has to be abstract. This abstract class cannot be instantiated.i.e., the below piece of code will not work. The code will not even compile.Parent object = new Parent();Purpose of Abstract Classes:Abstract classes are generally used where you want an amount of behaviour to be used by the class that extends the abstract class while at the same time giving options to the child class to provide a certain amount of behaviour itself.A Child Class extending the Abstract Class:public class Child extends Parent {public String getSon() {return "Sons Name";}public String getDaughter(){return "Daughters Name";}...... //Code specific to the Child class}
Can an abstract method be declared static?
Yes. Abstract methods can be declared static
What is abstract base class?
An abstract class is a class that cannot be directly instantiated. The purpose of such a class is to put some logic in a base class and force derived classes to implement the remaining functionality. Since the full functionality is only available in the derived class, the base class is declared as abstract so that it cannot be instantiated directly.
Does the abstract classes contain implementation for methods?
An Abstract class is a special kind of class that cannot be instantiated. It has one or more methods which are not implemented in the class. These methods are declared abstract and they do not contain any code inside them.Ex:abstract class Parent {public abstract String getSon();public abstract String getDaughter();........//More methods that contain specific behaviour/code in them}The above is an abstract class "Parent" that has a lot of functionality but it has declared two abstract methods which have no code inside them. Any class that has one or more abstract methods has to be abstract. This abstract class cannot be instantiated.i.e., the below piece of code will not work. The code will not even compile.Parent object = new Parent();Purpose of Abstract Classes:Abstract classes are generally used where you want an amount of behaviour to be used by the class that extends the abstract class while at the same time giving options to the child class to provide a certain amount of behaviour itself.A Child Class extending the Abstract Class:public class Child extends Parent {public String getSon() {return "Sons Name";}public String getDaughter(){return "Daughters Name";}...... //Code specific to the Child class}You can also have methods that have code implementation in the abstract class but those methods cannot have the abstract keyword in their method declaration.
