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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.
Can you have a final abstract class?
No. The abstract keyword means that you cannot instantiate the class unless you extend it with a subclass. The final keyword means that you cannot create subclasses of that class.Combining them would lead to an unusable class, so the compiler will not let this happen.
Which keyword is used to declare a class?
There is no keyword for it. You can use a variable of 1 class in another only id the other class is derived from the 1st class.Although you can use the variable of an object of a class in another class using object.variable
What does the keyword extends mean in BlueJ?
The "extends" keyword in Java is how you declare a subclass.class Base {void foo() {}}class Sub extends Base { //Sub is now a subclass of Basevoid begin(){Sub s = new Base(); //cannot do this the other way around!}}
Why we can't create object for Container class using new keyword?
It is an abstract class so you can't instantiate it directly, but have to use a subclass instead.
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.
Can you have a final abstract class?
No. The abstract keyword means that you cannot instantiate the class unless you extend it with a subclass. The final keyword means that you cannot create subclasses of that class.Combining them would lead to an unusable class, so the compiler will not let this happen.
Which keyword is used to declare a class?
There is no keyword for it. You can use a variable of 1 class in another only id the other class is derived from the 1st class.Although you can use the variable of an object of a class in another class using object.variable
What happens if an abstract modifier is applied to class. Explain?
The classes which have one or more abstract methods are abstract. To declare a class as abstract, use the abstract keyword in front of the class keyword, before the class declaration. Abstract classes cannot be instantiated. Similarly the new keyword cannot be used to create an object of the abstract class. Remember that the constructors and static variables cannot be declared as abstract. Any subclass of an abstract class must either implement all of the abstract methods in the superclass or be itself declared abstract.
What does the keyword extends mean in BlueJ?
The "extends" keyword in Java is how you declare a subclass.class Base {void foo() {}}class Sub extends Base { //Sub is now a subclass of Basevoid begin(){Sub s = new Base(); //cannot do this the other way around!}}
Why we can't create object for Container class using new keyword?
It is an abstract class so you can't instantiate it directly, but have to use a subclass instead.
When do you declare a class as final?
By using the final keyword in the class declaration statement. Ex: public final class Test {...}
What is the keyword used to declare a class which cannot be instantiated?
abstract all lower case.
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 the relationship between inheritance methods and the keyword final?
They are inversely related. That is: If you declare a method as final you cannot overridden in the child class If you declare a class as final you cannot inherit it in any other class.
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.
Is there any way that we can stop our class being inherited by subclass in C?
Yes. Declare the class final to prevent further inheritance. We can also do this on a function-by-function basis to prevent derived classes from overriding individual virtual methods.
