- Can abstract class have constructor?
- Can constructor contains return type?
- What is true final class?
- Can a class run without constructor?
- Can we declare constructor as protected?
- What is the purpose of a private constructor?
- Can a constructor be static?
- Can we override static method?
- What happens if there is no constructor?
- Can we override constructor in C++?
- Why constructor is not overridden?
- Can we inherit a constructor?
- Can you use this () and super () both in a constructor?
- Can we override private method?
- Can constructor take any number of parameters?
- What is the difference between method and constructor?
- Can we override private constructor in Java?
- Why can’t a constructor be final?
Can abstract class have constructor?
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 constructor contains return type?
No, constructor does not have any return type in Java. Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. Mostly it is used to instantiate the instance variables of a class.
What is true final class?
What is true of final class? Explanation: Final class cannot be inherited. … Explanation: Only one copy of static variables are created when a class is loaded. Each object instantiated has its own copy of instance variables.
Can a class run without constructor?
Java doesn’t require a constructor when we create a class. … The compiler automatically provides a public no-argument constructor for any class without constructors. This is called the default constructor. If we do explicitly declare a constructor of any form, then this automatic insertion by the compiler won’t occur.
Can we declare constructor as protected?
protected: If you declare constructor as protected, any other child classes or classes within the same package can instantiate this class.
What is the purpose of a private constructor?
Private constructors are used to prevent creating instances of a class when there are no instance fields or methods, such as the Math class, or when a method is called to obtain an instance of a class. If all the methods in the class are static, consider making the complete class static.
Can a constructor be static?
No, we cannot define a static constructor in Java, If we are trying to define a constructor with the static keyword a compile-time error will occur. In general, static means class level. A constructor will be used to assign initial values for the instance variables.
Can we override static method?
Can we Override static methods in java? We can declare static methods with same signature in subclass, but it is not considered overriding as there won’t be any run-time polymorphism.
What happens if there is no constructor?
If you don’t specify a constructor, a default constructor will be generated by the compiler. However, any member variable that is not initialized when it’s declared will be null. In other words, if you don’t assign a value to grid (like you do in your example) it will be null.
Can we override constructor in C++?
No , constructor can never be overridden . It’s because constructor acts at class level and it’s unique for each class created in Java or any Oop language. Constructor can only be accessed by other classes to create it’s object , but cant override it.
Why constructor is not overridden?
Constructor Overriding is never possible in Java. This is because, Constructor looks like a method but name should be as class name and no return value. Overriding means what we have declared in Super class, that exactly we have to declare in Sub class it is called Overriding.
Can we inherit a constructor?
A subclass inherits all the members (fields, methods, and nested classes) from its superclass. Constructors are not members, so they are not inherited by subclasses, but the constructor of the superclass can be invoked from the subclass.
Can you use this () and super () both in a constructor?
Both this() and super() are constructor calls. Constructor call must always be the first statement. So you either have super() or this() as first statement. Both this() and super() are constructor calls, and constructor call must be the first (and only first) call in a constructor.
Can we override private method?
No, we cannot override private or static methods in Java. Private methods in Java are not visible to any other class which limits their scope to the class in which they are declared.
Can constructor take any number of parameters?
A Java class constructor initializes instances (objects) of that class. Typically, the constructor initializes the fields of the object that need initialization. Java constructors can also take parameters, so fields can be initialized in the object at creation time.
What is the difference between method and constructor?
Constructor is used to initialize an object whereas method is used to exhibits functionality of an object. Constructors are invoked implicitly whereas methods are invoked explicitly. Constructor does not return any value where the method may/may not return a value.
Can we override private constructor in Java?
Private constructors are also used to prevent any instantiation, if you have a utility class which just has static methods. Constructor is meant for a class. It cant be overridden under any circumstances.
Why can’t a constructor be final?
No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors. Therefore, java does not allow final keyword before a constructor.