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No. Because, what is the guarantee that when the super class code is being executed there will always be a sub class?
But, the other way round - sub class object accessing a super class variable is possible because, if a sub class uses inheritance to extend from another class, then it is 100% sure that the parent class is going to be around. So a sub class can access the super class variable.
I don't think so. It doesn't really make much sense, since the superclass isn't even aware of the existence of the subclass. On the other hand, the subclass IS aware of the superclass, and may access the variable, depending on the access specifiers used.
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When a subclass can call a parent's class constructor?
A subclass invokes its base class constructor at the point of instantiation. That is; you cannot instantiate a subclass object without first constructing its base class, which is done automatically.
How super class variable can be used to refer the sub class object?
The super variable is not a reference to a subclass. It is a reference to the superclass. class MyClass { void printType() { System.out.println("This is a MyClass"); } // MySubClass is a subclass of MyClass. Within this class, the super keyword // refers to MyClass. static class MySubClass extends MyClass { void printType() { // Tell Java we also want to call the printType method of the super class super.printType(); System.out.println("This is a MySubClass"); } } }
Is every class in java is subclass of itself?
A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.
In java why method defined in super class need not to defined in subclass?
In Java, or in any object oriented language such as C++, a method defined in super (parent) class does not need to be defined in a subclass, because that is the primary purpose of inheritance. Object oriented programming allows you to define and declare a class that implements the behavior for an object. Inheritance allows you to refine, or subclass, that class by "reusing" all of the functionality of the parent class into the sub class, adding additional definition and declaration for the sub class. If the subclass needs to change a parent class method, it can overload that method. This is called abstraction.
Can you call an abstract method from a non abstract method in java?
We can't call (i.e, execute) an abstract method in java because these methods don't contain any code to execute!In some special cases like when an abstract method is overridden in a subclass, and when we are using super class reference variable( which is referring that subclass object), it appears that we are calling abstract method in super class. But actually the code in the subclass method is being executed.Example:abstract class SuperClass{abstract void show(); //abstract method in super class}class SubClass extends SuperClass{void show(){ //show() of SuperClass overridden in SubClassSystem.out.println("SubClass Method");}}class Example{public static void main(String... args){SuperClass sup=new SubClass();sup.show(); //SubClass show() will be executed !!!}}
When a subclass can call a parent's class constructor?
A subclass invokes its base class constructor at the point of instantiation. That is; you cannot instantiate a subclass object without first constructing its base class, which is done automatically.
How super class variable can be used to refer the sub class object?
The super variable is not a reference to a subclass. It is a reference to the superclass. class MyClass { void printType() { System.out.println("This is a MyClass"); } // MySubClass is a subclass of MyClass. Within this class, the super keyword // refers to MyClass. static class MySubClass extends MyClass { void printType() { // Tell Java we also want to call the printType method of the super class super.printType(); System.out.println("This is a MySubClass"); } } }
Is every class in java is subclass of itself?
A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.A class can be a subclass of another class, not of itself.
In java why method defined in super class need not to defined in subclass?
In Java, or in any object oriented language such as C++, a method defined in super (parent) class does not need to be defined in a subclass, because that is the primary purpose of inheritance. Object oriented programming allows you to define and declare a class that implements the behavior for an object. Inheritance allows you to refine, or subclass, that class by "reusing" all of the functionality of the parent class into the sub class, adding additional definition and declaration for the sub class. If the subclass needs to change a parent class method, it can overload that method. This is called abstraction.
Which object-oriented concept defines the relationship between a subclass and a super class?
Inheritance
Can you call an abstract method from a non abstract method in java?
We can't call (i.e, execute) an abstract method in java because these methods don't contain any code to execute!In some special cases like when an abstract method is overridden in a subclass, and when we are using super class reference variable( which is referring that subclass object), it appears that we are calling abstract method in super class. But actually the code in the subclass method is being executed.Example:abstract class SuperClass{abstract void show(); //abstract method in super class}class SubClass extends SuperClass{void show(){ //show() of SuperClass overridden in SubClassSystem.out.println("SubClass Method");}}class Example{public static void main(String... args){SuperClass sup=new SubClass();sup.show(); //SubClass show() will be executed !!!}}
What is a sub class?
In object oriented programming approach subclass is derived from parent class. This term is generally used in concept called "Inheritance" Example [PHP] class A { //class A definition } class B extends A { //class B definition } In above example class A is parent class and class B is subclass/child class .
What is sub classes?
In object oriented programming approach subclass is derived from parent class. This term is generally used in concept called "Inheritance" Example [PHP] class A { //class A definition } class B extends A { //class B definition } In above example class A is parent class and class B is subclass/child class .
What is the use of the instanceof keyword in Java?
That is used to verify whether an object is based on the specified class (or a subclass).
What is heritance in java?
With inheritance, you can use methods and fields from the superclass in a subclass. So for example when I have a class Person with fields age and gender, I can make a subclass Student. a Student object has always the fields from its superclass Person (age and gender), but you can make extra fields for a Student object. The same is true for methods: a method defined in the Person class can also be used on a Student object because Student is a subclass from Person. Got it? ;)
What is class cast exception?
The class case exception is thrown when an object A of class type B is cast to a class type C where C is neither B nor its subclass.
What is object overridding?
Overriding is an Object-Oriented concept where a subclass overrides a parent class's method(s) so it can provide it's own implementation.
