Quick Answer: Can A Private Class Be Extended In Java?

Can you extend a private class?

The answer is you can’t extend the Parent class if it has a private default constructor.

You have to make the constructor available to the subclass.

In this case you need to have a default constructor that have a protected or public or default access modifier..

Can private class be inherited in Java?

A subclass does not inherit the private members of its parent class. However, if the superclass has public or protected methods for accessing its private fields, these can also be used by the subclass. A nested class has access to all the private members of its enclosing class—both fields and methods.

Can we inherit private method?

A java private member cannot be inherited as it is available only to the declared java class. Since the private members cannot be inherited, there is no place for discussion on java runtime overloading or java overriding (polymorphism) features.

Can constructor be 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.

How many classes can you extend in Java?

one classA class can extend only one class, but implement many interfaces. An interface can extend another interface, in a similar way as a class can extend another class.

Can we inherit multiple classes in Java?

When one class extends more than one classes then this is called multiple inheritance. … Java doesn’t allow multiple inheritance.

Where is singleton class used?

Singleton classes are used for logging, driver objects, caching and thread pool, database connections. An implementation of singleton class should have following properties: It should have only one instance : This is done by providing an instance of the class from within the class.

Can private methods be overloaded in Java?

Yes, we can overload private methods in Java but, you can access these from the same class.

Can I extend 2 classes in Java?

Java does not support multiple inheritance, that’s why you can’t extend a class from two different classes at the same time. Rather, use a single class to extend from, and use interfaces to include additional functionality.

Can we override private and final methods?

No, We can not override private method in Java, just like we can not override static method in Java. … private methods are not even visible to Child class, they are only visible and accessible in the class on which they are declared. private keyword provides highest level of Encapsulation in Java.

Can we overload private and final methods?

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.

Is multiple inheritance possible in Java?

The Java programming language supports multiple inheritance of type, which is the ability of a class to implement more than one interface. … As with multiple inheritance of implementation, a class can inherit different implementations of a method defined (as default or static) in the interfaces that it extends.

Can singleton class be serialized?

Conclusion: Singleton class can also be serialized by keeping readResolve() method in the Singleton class. This may be a familiar solution but just in case for reference. So if we execute above code we will get following behaviour: “it has created two objects and one static reference for INSTANCE.

What is the purpose of a singleton?

The purpose of the singleton class is to control object creation, limiting the number of objects to only one. The singleton allows only one entry point to create the new instance of the class.

Can we extend main class in Java?

Short answer is NO,we can not override main method in java. Reason is very simple.As main method is static and we know very well that we can not override static methods in Java,hence main method could not be overridden. … But as we can see in output ,in both calls ,main method of Application class is called.

Can we extend a singleton class?

All you need to extend a singleton class is a constructor with protected or package-default in the singleton class. If there are only private constructors you simply won’t be able to extend it. If there are public constructors then it’s not a singleton class.

Can we override private method?

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 override?

Constructor looks like method but it is not. It does not have a return type and its name is same as the class name. But, a constructor cannot be overridden. If you try to write a super class’s constructor in the sub class compiler treats it as a method and expects a return type and generates a compile time error.