- Can a class be declared as static?
- When should we use abstract class?
- What is difference between abstract class and interface?
- Can abstract class be inherited?
- Can abstract class have constructor?
- Can an abstract method have a body?
- Can we override static method?
- Is object an abstract class?
- What is the benefit of using abstract class?
- Why can’t we create the object of an abstract class?
- What is the purpose of an abstract method?
Can a class be declared as static?
So, Yes, you can declare a class static in Java, provided the class is inside a top-level class.
Such clauses are also known as nested classes and they can be declared static, but if you are thinking to make a top-level class static in Java, then it’s not allowed..
When should we use abstract class?
The short answer: An abstract class allows you to create functionality that subclasses can implement or override. An interface only allows you to define functionality, not implement it. And whereas a class can extend only one abstract class, it can take advantage of multiple interfaces.
What is difference between abstract class and interface?
Main difference is methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior. … A Java class can implement multiple interfaces but it can extend only one abstract class.
Can abstract class be inherited?
A user must use the override keyword before the method which is declared as abstract in child class, the abstract class is used to inherit in the child class. An abstract class cannot be inherited by structures. It can contains constructors or destructors. It can implement functions with non-Abstract methods.
Can abstract class have constructor?
Yes, Abstract Classes can have constructors ! Abstract class can have a constructor though it cannot be instantiated. But the constructor defined in an abstract class can be used for instantiation of concrete class of this abstract class.
Can an abstract method have a body?
Java Abstract Method Abstract methods are declaration only and it will not have implementation. It will not have a method body. 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.
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).
Is object an abstract class?
The Object class is used in reflection so code can call methods on instances of indeterminate type, i.e. ‘Object. class. … According to Sun, An abstract class is a class that is declared abstract—it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed.
What is the benefit of using abstract class?
The advantage of using an abstract class is that you can group several related classes together as siblings. Grouping classes together is important in keeping a program organized and understandable. The picture shows this program after its object has been constructed.
Why can’t we create the object of an abstract class?
As you cannot force, you cannot create an instance of an abstract class. … Because an abstract class is an incomplete class (incomplete in the sense it contains abstract methods without body and output) we cannot create an instance or object; the same way you say for an interface.
What is the purpose of an abstract method?
An abstract method is how you say, “Here’s something that all the things that extend this class have to do, but they each get to specify how exactly they will do it.” Failure to provide the implementation will cause a compilation error. Abstract methods should be implemented in subclasses of this abstract class.