crostreasure.blogg.se

1. #Java interview questions for automation testing how to#
2. #Java interview questions for automation testing code#

This subclass constructor has super in the first line that calls constructor of an abstract class. When we create an object of subclass of an abstract class, it calls the constructor of subclass. 🅰 We cannot create an object of abstract class but we can create an object of subclass of abstract class. Why abstract class has constructor even though you cannot create object?

We cannot create an instance of abstract class whereas, we can create an instance of class.ī. What is the difference between abstract class and class? 🅰 Refer to this tutorial: Class vs Interfaceĥ9. What is the difference between class and interface? 🅰 Go to this tutorial: 12 Difference between abstract class and interfaceĥ8. What is the difference between abstract class and interface? For example, serializable, cloneable, remote, etc.ĥ7. 🅰 An interface that has no variable and method is known as marker interface. Therefore, an interface method cannot be declared as final. 🅰 No, because its implementation is provided by another class. 🅰 Yes, from Java 8 onwards, we can declare static and default methods in an interface. Is it allowed to declare an interface method as static? It is basically a kind of class but can have only abstract methods declaration and constants as members.ĥ4. 🅰 An interface in Java is a mechanism that is used to achieve complete abstraction. 🅰 An abstract method is generally used when the same method has to perform different tasks depending on the object calling it.Īn abstract class is used when we need to share the same method to all non-abstract subclasses with their own specific implementations. When to use abstract class and abstract method in Java? 🅰 Yes, we can create a reference for an abstract class only when the object being provided the implementation for the abstract class.ĥ2. Can we create a reference for an abstract class? If you try to instantiate, you will get compile time error.ĥ1. This is because abstract class is not a concrete class. 🅰 No, we cannot create an instance of abstract class in Java. Can we create an object of abstract class in Java? Therefore, a method can be either abstract or final in Java.ĥ0. 🅰 No, because abstract method needs to be overridden by child class whereas, a final method cannot be overridden. Is it allowed to declare a method abstract as well as final? 🅰 No, if there is any abstract method in a class then class must be declared with abstract keyword.Ĥ9. Can there be any abstract method without abstract class in Java? It is basically done to avoid instance creation of the class.Ĥ8. Can an abstract class be defined without any abstract methods? 🅰 A method which is declared with abstract modifier and has no implementation (means no body) is called an abstract method. An abstract class has to be extended and its abstract methods must be implemented by a child class. 🅰 A class that is declared with an abstract keyword is called abstract class. 🅰 There are two ways by which we can achieve abstraction in java.

#Java interview questions for automation testing how to#

How to achieve or implement abstraction in Java?

#Java interview questions for automation testing code#

🅰 Abstraction is used to hide the implementation details whereas, encapsulation binds code and data into a single unit.Ĥ4. What is the difference between abstraction and encapsulation?