Can a abstract class be declared 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 a abstract method be declared as final justify?

Declaring abstract method final

Similarly, you cannot override final methods in Java. But, in-case of abstract, you must override an abstract method to use it. Therefore, you cannot use abstract and final together before a method.

Can abstract class be final or sealed?

An abstract class can contain sealed methods. The abstract method or class cannot be declared as sealed. A subclass of an abstract class can only be instantiated if it implements all of the abstract methods of its superclass. Such classes are called concrete classes to differentiate them from abstract classes.

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 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.

Why class cant be abstract and final | Can abstract class be final in java | Java interview question

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 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.

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 abstract class have static and final methods?

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 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 abstract can be sealed?

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

Can we have abstract class as sealed?

A sealed class cannot be used as a base class. For this reason, it cannot also be an abstract class.

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 abstract class have final private modifiers?

A Java class containing an abstract class must be declared as abstract class. An abstract method can only set a visibility modifier, one of public or protected. That is, an abstract method cannot add static or final modifier to the declaration.

What is abstract class and final class?

An abstract class is a class declared with an abstract keyword, which is a collection of abstract and non-abstract methods. But, the final class is a class declared with the final keyword, which restricts other classes from accessing it. Thus, this is the main difference between abstract class and final class in Java.

Can a Java class be final?

A class can be made final by using the final keyword. The final class cannot be inherited and so the final keyword is commonly used with a class to prevent inheritance.

Can a main () method be declared final?

Yes, we can declare the main () method as final in Java. The compiler does not throw any error. If we declare any method as final by placing the final keyword then that method becomes the final method.

Can singleton class be inherited in Java?

Unlike static classes, Singleton classes can be inherited, can have base class, can be serialized and can implement interfaces.

Can we create immutable class in Java?

Immutable class in java means that once an object is created, we cannot change its content. In Java, all the wrapper classes (like Integer, Boolean, Byte, Short) and String class is immutable. We can create our own immutable class as well.

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 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 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.