How to prevent subclassing in java?

Asked by: Dr. Hilma Hegmann IV
Score: 4.9/5 (64 votes)

You can prevent a class from being subclassed by using the final keyword in the class's declaration. Similarly, you can prevent a method from being overridden by subclasses by declaring it as a final method. An abstract class can only be subclassed; it cannot be instantiated.

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Also, How do you stop inheritance in Java?

To prevent inheritance, use the keyword "final" when creating the class. The designers of the String class realized that it was not a candidate for inheritance and have prevented it from being extended.

In respect to this, Is it possible to restrict inheritance?. 1 Answer. You cannot restrict inheritance in javascript. If you have a public constructor function that initializes an object, any other object can use it to make a derived object.

Just so, How do you stop a method overriding in Java?

Different Ways to Prevent Method Overriding in Java
  1. Using a static method.
  2. Using private access modifier.
  3. Using default access modifier.
  4. Using the final keyword method.


What are the ways to avoid object creation?

You can often avoid creating unnecessary objects by using static factory methods (Item 1) in preference to constructors on immutable classes that provide both. For example, the static factory method Boolean. valueOf(String) is almost always preferable to the constructor Boolean(String).

43 related questions found

Is object creation expensive in Java?

The results show that creating a short lived object is quite cheap, even including the cost of garbage collection. ... JVM monitoring for the “Creating an object whose reference is held in a collection for some time – ArrayList” case. Longer lived objects in a collection do cause significant GC overhead.

What is lazy initialization Java?

In computer programming, lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed. It is a kind of lazy evaluation that refers specifically to the instantiation of objects or other resources.

Which method we Cannot be override?

No, we cannot override static methods because method overriding is based on dynamic binding at runtime and the static methods are bonded using static binding at compile time. So, we cannot override static methods. The calling of method depends upon the type of object that calls the static method.

What is a final method?

You use the final keyword in a method declaration to indicate that the method cannot be overridden by subclasses. The Object class does this—a number of its methods are final .

Can we prevent Method Overriding without using final?

Final methods can not be overridden

By making a method final we are adding a restriction that derived class cannot override this particular method.

Can we override static method?

Static methods cannot be overridden because they are not dispatched on the object instance at runtime. The compiler decides which method gets called. Static methods can be overloaded (meaning that you can have the same method name for several methods as long as they have different parameter types).

How can we implement multiple inheritance?

The only way to implement multiple inheritance is to implement multiple interfaces in a class. In java, one class can implements two or more interfaces. This also does not cause any ambiguity because all methods declared in interfaces are implemented in class.

Can static method be overloaded?

Can we overload static methods? The answer is 'Yes'. We can have two or more static methods with the same name, but differences in input parameters. For example, consider the following Java program.

Can final methods be overridden?

Can We Override a Final Method? No, the Methods that are declared as final cannot be Overridden or hidden. ... It is noteworthy that abstract methods cannot be declared as final because they aren't complete and Overriding them is necessary.

Can final method be overloaded?

private and final methods can be overloaded but they cannot be overridden. It means a class can have more than one private/final methods of same name but a child class cannot override the private/final methods of their base class. ... Argument list should be different while doing method overloading.

Can we override private method in Java?

No, we cannot override private or static methods in Java. Private methods in Java are not visible to any other class which limits their scope to the class in which they are declared.

Can a constructor be final?

No, a constructor can't be made final. A final method cannot be overridden by any subclasses. ... But, in inheritance sub class inherits the members of a super class except constructors. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.

Can we inherit final method in Java?

No, we cannot override a final method in Java. The final modifier for finalizing the implementations of classes, methods, and variables. We can declare a method as final, once you declare a method final it cannot be overridden.

What is difference between static and final?

Static is used to define the class member that can be used independently of any object of the class. Final is used to declare a constant variable or a method that cannot be overridden or a class that cannot be inherited. This is the main difference between static and final.

Why we Cannot 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.

Can constructor be overridden?

Constructors are not normal methods and they cannot be "overridden". Saying that a constructor can be overridden would imply that a superclass constructor would be visible and could be called to create an instance of a subclass.

Can we execute a program without main?

Yes You can compile and execute without main method By using static block. But after static block executed (printed) you will get an error saying no main method found.

Is Lazy initialization good?

Lazy initialization is primarily used to improve performance, avoid wasteful computation, and reduce program memory requirements. These are the most common scenarios: When you have an object that is expensive to create, and the program might not use it.

How lazy initialization works in Java?

The Lazy Initialization technique consists of checking the value of a class field when it's being used. If that value equals to null then that field gets loaded with the proper value before it is returned.

What is lazy initialization in spring?

By default in Spring, all the defined beans, and their dependencies, are created when the application context is created. In contrast, when we configure a bean with lazy initialization, the bean will only be created, and its dependencies injected, once they're needed.