- Which is better abstract class or interface?
- How many default constructors can a class have?
- Why constructor has no return type?
- Can abstract class have body?
- Can a constructor be final?
- Can we make abstract class as final?
- What happens if a user forgets to define a constructor inside a class?
- Why does an abstract class have a constructor?
- Can constructor be static?
- Can we declare abstract class as static?
- Can an abstract class be private?
- Can an abstract class have a constructor?
- Can a constructor have a return type C++?
- Can constructor be private?
Which is better abstract class or interface?
The short answer: An abstract class allows you to create functionality that subclasses can implement or override.
An interface only allows you to define functionality, not implement it.
And whereas a class can extend only one abstract class, it can take advantage of multiple interfaces..
How many default constructors can a class have?
one default constructorA class can only have one default constructor.
Why constructor has no return type?
So the reason the constructor doesn’t return a value is because it’s not called directly by your code, it’s called by the memory allocation and object initialization code in the runtime. Its return value (if it actually has one when compiled down to machine code) is opaque to the user – therefore, you can’t specify it.
Can abstract class have body?
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 a constructor be final?
No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … But, in inheritance sub class inherits the members of a super class except constructors. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.
Can we make abstract class as final?
In short, an abstract class cannot be final in Java, using both abstract and final modifier with a class is illegal in Java. … An abstract method must be overridden to be useful and called but when you make the abstract method final it cannot be overridden in Java, hence there would be no way to use that method.
What happens if a user forgets to define a constructor inside a class?
Also if any user forgets to define init() function then no object will be initialized whereas if any constructor is not defined in any class the class provides a default constructor for initialization. 3. What is a copy constructor?
Why does an abstract class have a constructor?
The main purpose of the constructor is to initialize the newly created object. In abstract class, we have an instance variable, abstract methods, and non-abstract methods. … The constructor inside the abstract class can only be called during constructor chaining i.e. when we create an instance of sub-classes.
Can constructor be static?
A static constructor does not take access modifiers or have parameters. A class or struct can only have one static constructor. Static constructors cannot be inherited or overloaded. A static constructor cannot be called directly and is only meant to be called by the common language runtime (CLR).
Can we declare abstract class as static?
Yes, abstract class can have Static Methods. The reason for this is Static methods do not work on the instance of the class, they are directly associated with the class itself.
Can an abstract class be 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 an abstract class have a 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 a constructor have a return type C++?
Constructors don’t have return type. A constructor is automatically called when an object is created. If we do not specify a constructor, C++ compiler generates a default constructor for us (expects no parameters and has an empty body).
Can constructor be private?
Yes, we can declare a constructor as private. If we declare a constructor as private we are not able to create an object of a class. We can use this private constructor in the Singleton Design Pattern.