When a constructor is protected, users are prevented from creating a class instance outside of the package. If a variable or method is protected during overriding, it can only be overridden by another subclass using the public or protected modifier. Interfaces and outer classes are not protected.
What happens if constructor of class A is made protected?
5. What happens if the class A constructor is made private? It is impossible to create an instance of a class from outside the class if the constructor is made private.
Can we declare constructor as protected in C++?
Constructors typically have public accessibility so that programs outside of the definition of the class or its inheritance hierarchy can produce objects of that class. However, a constructor can also be marked as protected or private. Constructors can be listed as inline, explicit, friend, or constexpr in their declarations.
What happens if we declare constructor as final?
finalizing the constructor
whenever you extend a class in inheritance. With the exception of the constructors, every member of the superclass is inherited by the child class. In other words, since constructors in Java cannot be inherited, they cannot be overridden. Therefore, it makes no sense to write final before constructors.
Can we declare constructor as protected in Java?
Yes, we are allowed to make a constructor private. We are unable to create an object of a class if we declare a constructor as private.
What is the true about protected constructor?
What is the truth regarding the protected constructor? Using the protected access modifier, classes in the same package and child classes of the parent class can access the constructor.
Can we use protected in constructor?
Constructors may use public, protected, and private modifiers. When building a singleton class in Java, we can use a private constructor.
Can protected methods be overridden?
Yes, a subclass may override a superclass’s protected method. The subclass overridden method cannot have a weaker access specifier if the superclass method is protected. Instead, it can have protected or public access (but not default or private).
Can we declare constructor as public?
No, constructors can be default, protected, private, or public (no access modifier at all). Even if something is made private, no one will be able to access it. Simply put, it means that only those in the class have access to it. Private constructor is therefore also helpful.
What does Protected mean in C++?
Access to class members is specified by the protected keyword up until the next access specifier (public or private), or the conclusion of the class definition. Protected class members can only be used by those who can: the class that originally declared these members’ member functions.
Why we cant declare constructor as final?
With the exception of the constructors, every member of the superclass is inherited by the child class. In other words, since constructors in Java cannot be inherited, they cannot be overridden. Therefore, it is absurd to write final before constructors. Java forbids the use of the final keyword before a constructor as a result.
Can we declare constructor as abstract?
Yes, a constructor can be present in an abstract class. In an abstract class, you can overload as many constructors as you like. The initial state of the objects extending the abstract class can be initialized using these contractors.
Why protected is used in Java?
Attributes, methods, and constructors can be made accessible to other members of the same package and subclasses by using the protected keyword as an access modifier.
Can abstract class have protected constructor?
Only derived types are permitted to call constructors on abstract types. An abstract type with a public constructor is improperly designed because you cannot create instances of an abstract type and public constructors create instances of a type.
What is true about private constructor Mcq?
1 Response. To clarify: Private constructor objects can only be created inside of classes. Singleton pattern uses a private constructor.
Which of the following is correct about constructor?
Which of the following statements is correct about constructors?
| 1) | Static constructors can use optional arguments. |
|---|---|
| 3) | If we do not provide a constructor, then the compiler provides a zero-argument constructor. |
| 4) | Overloaded constructors cannot use optional arguments. |
| 5) | NULL |
Can we use protected for a class in Java?
No, a top-level class cannot be made private or protected. It may be default or public (no modifier).
What is protected access specifier in Java?
protected: The keyword protected is used to specify the protected access modifier. The protected methods or data members can be accessed by subclasses in the same package or in other packages.
Can constructor throw an exception?
Constructors may, in fact, raise exceptions in Java. An object is also referred to as an instance of a class, and a constructor is a special kind of method that is used to create an object of a class using the new keyword.
Why protected modifier is used?
The protected modifier designates that the member can only be accessed by a subclass of its class in another package as well as within its own package (like with package-private). The access to members that each modifier permits is displayed in the following table.
Can we extend protected class?
Class is defined as protected, so it cannot be extended from a package outside of its own (not visible). And since it will then become the default access, which is permitted, if it cannot be extended, maintaining it as protected is pointless.
Can we inherit static method in Java?
Instance variables of any objects belonging to the class in which a static method is defined are not used. Static methods do not make use of variables; instead, they compute something from all the data in the parameters. Java allows us to inherit static methods.
Can a constructor be overridden?
Constructor appears to be a method but is not one. Its name is the same as the class name and it lacks a return type. A constructor, however, cannot be replaced. The compiler treats it as a method, expects a return type, and produces a compile time error if you attempt to write a constructor for a super class in a sub class.
Why constructor is private in Singleton?
The object of our singleton class is provided to the target class by calling a static method in which the logic to provide only one object of singleton class is written, as opposed to any target class being able to instantiate our class directly by calling constructor.
Can we use void with constructor?
Keep in mind that the constructor cannot have a return type and that its name must correspond to the class name (like void ). Also take note that when an object is created, the constructor is called.
Can constructor be inherited?
Subclasses cannot inherit constructors because they are not members; however, they may call the constructor of the superclass.
What is the difference between protected and public?
The distinction between public and protected is that public can be accessed from outside the class, whereas protected cannot.
Is protected the same as private C++?
Members cannot be accessed (or viewed) from outside the class if they are private. protected members can be accessed in inherited classes but cannot be accessed from outside the class.
Why main method is static?
Java’s main() method is static by default, allowing the compiler to call it either before or after creating a class object. The main() method is where the compiler begins program execution in every Java program.
Why static methods Cannot be overridden?
The mechanism of dynamically binding the method call with the method body based on the parameters passed to the method call is called overloading. Static binding is used to bond static methods at compile time. Therefore, in Java, static methods cannot be overridden.
Can a constructor be synchronized?
Keep in mind that constructors cannot be synchronized; it is improper to use the synchronized keyword with a constructor. Because only the thread that creates an object should have access to it while it is being constructed, synchronizing constructors is illogical.
Why we Cannot use static and abstract?
A static method cannot be overridden or implemented in a child class because it belongs to the class rather than the individual object instance. Therefore, making a static method more abstract serves no purpose.
Can constructor be overloaded?
Yes! Java permits overloading of constructors. When loading a constructor, we create multiple constructors with the same name but various parameter types or numbers.
Can abstract class be inherited?
Structures cannot inherit from an abstract class. It might include constructors or destroyers. It can use non-Abstract methods to implement functions. There can be only one inheritance supported.
Can abstract method be private?
A class method that is private prevents access from outside the current class, including from its child classes. However, if a method is abstract, you must override it in a subclass before using it from the same class. The abstract method cannot be private as a result.
What happen if constructor is defined as private or protected in PHP?
To stop it from being called from outside the program, the constructor can be made private or protected. If so, the class can only be instantiated by a static method. Despite not belonging to the same object instance, they have access to private methods because they are in the same class definition.
What is the purpose of protected class?
Certain groups of people, such as women, older workers, people with disabilities, minorities, and others, are protected by anti-discrimination laws and are referred to as protected classes. See Managing Equal Employment Opportunity for more details.
Can we declare abstract static method?
declaring a static abstract method
If you want to use a method that is declared abstract in a class, you must override it in the subclass. However, with static methods, overriding is not an option. An abstract method cannot be static as a result.
Why abstract class has a constructor?
The initialization of a newly created object is the constructor’s primary function. There is an instance variable, abstract methods, and non-abstract methods in an abstract class. Abstract classes have a constructor because we need to initialize the non-abstract methods and instance variables.
What is multiple inheritance in OOP?
Some object-oriented computer programming languages allow for multiple inheritance, which allows an object or class to inherit characteristics from multiple parent objects or parent classes. It differs from single inheritance, which allows only one specific object or class to be inherited from.
When a copy constructor is called?
A copy constructor is a member function that uses another object from the same class to initialize a new object. The Copy constructor is typically used when an existing object is copied into a new object to create a new object.
Why do we use static constructor?
To initialize any static data or to carry out a specific task that needs to be done only once, a static constructor is used. Before the first instance is created or any static members are referenced, it is automatically called.
How many subclasses can a superclass have?
The number of subclasses a superclass can contain is unrestricted. In the same way, there is no restriction on the number of inheritance levels. A certain area of commonality can serve as the foundation for a hierarchy of classes. When a subclass derives from a superclass in Java, this is referred to as “extending” the superclass.
Can you have a class with no constructors?
When we create a class in Java, a constructor is not necessary. However, it’s critical to understand what takes place implicitly when constructors are not explicitly defined. For any class lacking constructors, the compiler will automatically provide a public no-argument constructor. The term “default constructor” refers to this.
Which type of constructor Cannot have a return type?
There cannot be a return type in a constructor (not even a void return type). A missing semicolon between the conclusion of a class definition and the first constructor implementation is a frequent cause of this error. The class is interpreted by the compiler as defining the constructor function’s return type, which results in the generation of C2533.
Can we override private methods?
Java does not allow overriding of static or private methods. The super class method will be hidden if a similar method with the same return type and method arguments is created in a child class; this is referred to as method hiding. Similar to how you cannot access a private method in a subclass, you also cannot override it.
Can static methods be private?
In Java 9, it is possible to include private methods or private static methods in an interface.
What is the difference between private public and protected in Java?
Access to protected members is possible from the same package’s child class. Access to package members is possible through the package’s child class. Public members are accessible from classes that are not children of the same package. Private members are inaccessible to classes that are not children of the same package.
Can outer class default?
A Java inner class is defined within another class’s body. A Java outer class can only have public or default access, whereas an inner class can be declared private, public, protected, or with default access.
Can constructor have try catch?
A constructor can throw an exception just like any other method because it is a method that is called when an object is created. Yes, just like in a method, a try-catch block can be written inside a constructor.