- Can abstract class have all concrete methods?
- Can an abstract class extend concrete?
- Who can access the class member with a private modifier?
- Can an abstract class be private?
- Can abstract method have return type?
- How do you override an abstract method?
- When abstract methods are used?
- Can an abstract class have a constructor C++?
- Can we declare final inside abstract class and interface both?
- Is it possible to overload main method?
- Can the main method be private?
- Can we declare abstract methods as static?
- Can abstract class have constructor?
- Can we override static method?
- Why can’t we instantiate an abstract class?
- Can abstract method have body?
- Can abstract class be inherited?
- Can main method be final?
Can abstract class have all concrete methods?
A class that is declared using “abstract” keyword is known as abstract class.
It can have abstract methods(methods without body) as well as concrete methods (regular methods with body).
A normal class(non-abstract class) cannot have abstract methods..
Can an abstract class extend concrete?
An abstract class always extends a concrete class ( java. … If you want to instantiate it, you will have to subclass it with a concrete implementation of those abstract methods and instantiate it through the concrete class. Just like you always do.
Who can access the class member with a private modifier?
Private: The private access modifier is specified using the keyword private. The methods or data members declared as private are accessible only within the class in which they are declared. Any other class of same package will not be able to access these members.
Can an abstract class be private?
Abstract classes are similar 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.
Can abstract method have return type?
An abstract method has no body. (It has no statements.) It declares an access modifier, return type, and method signature followed by a semicolon. A non-abstract child class inherits the abstract method and must define a non-abstract method that matches the abstract method.
How do you override an abstract method?
A non-abstract child class of an abstract parent class must override each of the abstract methods of its parent. A non-abstract child must override each abstract method inherited from its parent by defining a method with the same signature and same return type. Objects of the child class will include this method.
When abstract methods are used?
Abstract classes cannot be instantiated and are designed to be subclassed. They are used to provide some common functionality across a set of related classes while also allowing default method implementations.
Can an abstract class have a constructor C++?
A class with one (or more) virtual pure functions is abstract, and it can’t be used to create a new object, so it doesn’t have a constructor.
Can we declare final inside abstract class and interface both?
An interface is a pure abstract class. Hence, all methods in an interface are abtract , and must be implemented in the child classes. So, by extension, none of them can be declared as final .
Is it possible to overload main method?
Yes, you can overload main method in Java. … Yes, main method can be overloaded. Overloaded main method has to be called from inside the “public static void main(String args)” as this is the entry point when the class is launched by the JVM.
Can the main method be private?
Yes, we can declare the main method as private in Java. It compiles successfully without any errors but at the runtime, it says that the main method is not public.
Can we declare abstract methods as static?
You cannot create an abstract static method. … 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 abstract class have constructor?
Yes! Abstract classes can have constructors! Yes, when we define a class to be an Abstract Class it cannot be instantiated but that does not mean an Abstract class cannot have a constructor. Each abstract class must have a concrete subclass which will implement the abstract methods of that abstract class.
Can we override static method?
Static methods cannot be overridden because they are not dispatched on the object instance at runtime. The compiler decides which method gets called. Static methods can be overloaded (meaning that you can have the same method name for several methods as long as they have different parameter types).
Why can’t we instantiate an abstract class?
Because an abstract class is an incomplete class (incomplete in the sense it contains abstract methods without body and output) we cannot create an instance or object; the same way you say for an interface. You CAN instantiate an abstract class. You only need to provide a concrete subclass.
Can abstract method have body?
Java Abstract Method Abstract methods are declaration only and it will not have implementation. It will not have a method body. A Java class containing an abstract class must be declared as abstract class. An abstract method can only set a visibility modifier, one of public or protected.
Can abstract class be inherited?
A user must use the override keyword before the method which is declared as abstract in child class, the abstract class is used to inherit in the child class. An abstract class cannot be inherited by structures. It can contains constructors or destructors. It can implement functions with non-Abstract methods.
Can main method be final?
Yes, we can declare the main () method as final in Java. The compiler does not throw any error. If we declare any method as final by placing the final keyword then that method becomes the final method. The main use of the final method in Java is they are not overridden.