What is an abstract method?
An abstract method is a method that is declared without an implementation (without braces, and followed by a semicolon), like this: abstract void moveTo(double deltaX, double deltaY);
What is difference between abstract class and interface?
Classes can implement multiple interfaces, but only one abstract class. Abstract classes can contain non-abstract methods. They can both have methods, variables, and neither one can be instantiated. All variables declared in an interface are final, while an abstract class may contain non-final variables.
Can we inherit abstract class?
Abstract Class But, if a class has at least one abstract method, then the class must be declared abstract. If a class is declared abstract, it cannot be instantiated. To use an abstract class, you have to inherit it from another class, provide implementations to the abstract methods in it.
Can we override abstract method?
We use the abstract keyword to create abstract classes and methods. An abstract method doesn’t have any implementation (method body). A subclass must override all abstract methods of an abstract class. However, if the subclass is declared abstract, it’s not mandatory to override abstract methods.
Is it possible to inherit from multiple abstract classes in Java?
A: Because Java doesn’t support multiple inheritance. A: Java has a rule that a class can extend only one abstract class, but can implement multiple interfaces (fully abstract classes).
Can an interface extend an abstract class?
Remember, a Java class can only have 1 superclass, but it can implement multiple interfaces. Thus, if a class already has a different superclass, it can implement an interface, but it cannot extend another abstract class. Therefore interfaces are a more flexible mechanism for exposing a common interface.
Can we override the static method?
Can we override a static method? 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.
Can abstract class have constructor C++?
An abstract class can have constructor similar to normal class implementation. In the case of the destructor, we can declare a pure virtual destructor. It is important to have a destructor to delete the memory allocated for the class.