Can we declare abstract class as final?

In short, an abstract class cannot be final in Java, using both abstract and final modifiers with a class is illegal in Java.

Can you declare an abstract class as final?

If you declare a class abstract, to use it, you must extend it and if you declare a class final you cannot extend it, since both contradict with each other you cannot declare a class both abstract and final if you do so a compile time error will be generated.

Can we declare abstract class and interface as final?

Type of variables: Abstract class can have final, non-final, static and non-static variables. The interface has only static and final variables. Implementation: Abstract class can provide the implementation of the interface. Interface can't provide the implementation of an abstract class.

Can we develop final abstract class in Java?

The answer is simple, No, it's not possible to have an abstract method in a final class in Java.

Can abstract class be final sealed?

When a class is declared sealed, it cannot be inherited, abstract classes cannot be declared sealed.

Can we make an abstract class as final?

Can a abstract class be 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 abstract class have constructor?

Like any other classes in Java, abstract classes can have constructors even when they are only called from their concrete subclasses.

Can we declare class as final?

Note that you can also declare an entire class final. A class that is declared final cannot be subclassed. This is particularly useful, for example, when creating an immutable class like the String class.

Can we declare interface as final?

If you make an interface final, you cannot implement its methods which defies the very purpose of the interfaces. Therefore, you cannot make an interface final in Java. Still if you try to do so, a compile time exception is generated saying “illegal combination of modifiers − interface and final”.

Can we declare constructor as final?

No, a constructor can't be made final. A final method cannot be overridden by any subclasses. As mentioned previously, the final modifier prevents a method from being modified in a subclass. The main intention of making a method final would be that the content of the method should not be changed by any outsider.

Can we declare abstract class as 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 we declare interface as static?

No, we cannot declare interface methods as static because static methods can not be overridden.

Can we override static method?

Overloading is the mechanism of binding the method call with the method body dynamically based on the parameters passed to the method call. Static methods are bonded at compile time using static binding. Therefore, we cannot override static methods in Java.

Why abstract can't be the final What is the reason?

No, An abstract class can't be final because the final and abstract are opposite terms in JAVA. Reason: An abstract class must be inherited by any derived class because a derived class is responsible to provide the implementation of abstract methods of an abstract class.

Can a constructor be declared static?

Java constructor can not be static

One of the important property of java constructor is that it can not be static. We know static keyword belongs to a class rather than the object of a class. A constructor is called when an object of a class is created, so no use of the static constructor.

Can we declare constructor as 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.

Can we declare static methods as private?

Yes, we can have private methods or private static methods in an interface in Java 9.

Can we override protected method as private?

Yes, the protected method of a superclass can be overridden by a subclass. If the superclass method is protected, the subclass overridden method can have protected or public (but not default or private) which means the subclass overridden method can not have a weaker access specifier.

Can abstract class be a base class?

We can use an abstract class as a base class and all derived classes must implement abstract definitions. Important Points: Generally, we use abstract class at the time of inheritance.

Can we declare class as static in Java?

We can declare a class static by using the static keyword. A class can be declared static only if it is a nested class. It does not require any reference of the outer class. The property of the static class is that it does not allows us to access the non-static members of the outer class.

Can we create object of abstract class?

We cannot create objects of an abstract class. To implement features of an abstract class, we inherit subclasses from it and create objects of the subclass. A subclass must override all abstract methods of an abstract class.

Can interface be instantiated?

An interface can't be instantiated directly. Its members are implemented by any class or struct that implements the interface. A class or struct can implement multiple interfaces.

Can we declare abstract static method?

Declaring abstract method static

If you declare a method in a class abstract to use it, you must override this method in the subclass. But, overriding is not possible with static methods. Therefore, an abstract method cannot be static.

Can abstract class have body?

Abstract methods cannot have body. Abstract class can have static fields and static method, like other classes. An abstract class cannot be declared as final. Only abstract class can have abstract methods.

Can we declare local inner class as abstract?

Yes, we can declare local inner class as abstract.