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You cannot create an instance of an abstract class. For ex:
Public abstract AbsTest {
…
}
AbsTest ex = new AbsTest();
Lets say we have a class declaration AbsTest that is abstract and then I try to instantiate it, the compiler will give me an error stating that "An Abstract class cannot be instantiated"
What else can I help you with?
What is true about true about abstract data type Object of an abstract class type cant be created. We can derive classes from these abstract classes Object of an abstract class t?
True - an instance of an abstract class cannot be created. False - derive (subclass) from a class, not the object (the instance).
What is the need to create an abstract class without abstract?
Actually there is no need & most importantly - you cannot create an abstract class without using the abstract keyword
Is it possible to create a Abstract class without abstract keyword?
no
Can you instantiate an abstract class?
No. You must create a subclass of the abstract class in order to be able to instantiate it.
Can abstract class have constructors?
A constructor of a class in invoked when a object of that class is created. As an abstract class can't have an object, so we can't create a constructor of the abstract class. But we can create a constructor of a concrete subclass of that abstract class and we have to pass the object of that concrete subclass to the abstract class.
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 is an abstract class Write the syntax Declare a pure virtual function in an abstract class?
an abstract class is nothing but class which contains both abstract and concrete methods for abstract class we r nt create object Syntax for pure abstract class is abstract class x { public void abstract y(); public void abstract z(); public void abc() { }
What do you mean by Get instance?
It means create an object for a class. Instance refers to the obj of a class.
How do you create a concrete method inside abstract class?
The same way you create a concrete method in a concrete class. When a class is abstract, it can contain abstract methods. That doesn't mean that all methods must be abstract. Hope this helps.
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 an abstract factory pattern?
An abstract factory pattern is a creational design pattern which decouples the object creation by providing a group of individual factories by defining an abstract factory class.
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.
