How do you declare an abstract method?
To declare an abstract method, use this general form: abstract type method-name(parameter-list); As you can see, no method body is present. Any concrete class(i.e. class without abstract keyword) that extends an abstract class must override all the abstract methods of the class.
Can we define abstract class in Java?
An abstract class is a class that is declared abstract —it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed. When an abstract class is subclassed, the subclass usually provides implementations for all of the abstract methods in its parent class.
How do you initialize an abstract class?
We define an abstract class with the abstract modifier preceding the class keyword
- We define an abstract class with the abstract modifier preceding the class keyword.
- An abstract class can be subclassed, but it can’t be instantiated.
Which is used to create an abstract class in Java?
The abstract keyword is used to achieve abstraction in Java. It is a non-access modifier which is used to create abstract class and method. The role of an abstract class is to contain abstract methods.
Can we declare abstract class as final?
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.
Which of the following declare an abstract method in an abstract Java class?
The correct answer is option (B.) public abstract void method(); public abstract void method(); declares an abstract method in an abstract Java class. A method without body (no implementation) is known as abstract method.
What is the syntax of abstract class in Java Mcq?
Explanation: The syntax of abstract class in java is abstract class A{}. 4.
Can we create reference of abstract class?
No, we can’t create an object of an abstract class. But we can create a reference variable of an abstract class. The reference variable is used to refer to the objects of derived classes (subclasses of abstract class).
Can we declare abstract method 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.
Can we declare abstract methods as synchronized?
No, you can’t synchronize abstract methods in Java. When you synchronize a method that implies that you are synchronizing the code in it, i.e. when one thread is accessing the code of a synchronized method no other thread is allowed to access it.