Here is a list of Java interview Questions and Answers
What is Polymorphism?
Polymorphism is briefly described as “one interface, many implementations”. Polymorphism is a characteristic of being able to assign a different meaning or usage to something in different contexts – specifically, to allow an entity such as a variable, a function, or an object to have more than one form. There are two types of polymorphism:
Compile time polymorphism is method overloading whereas Runtime time polymorphism is done using inheritance and interface.
What is multiple inheritance? Is it supported by Java?
If a child class inherits the property from multiple classes is known as multiple inheritance. Java does not allow to extend multiple classes.
The problem with multiple inheritance is that if multiple parent classes have a same method name, then at runtime it becomes difficult for the compiler to decide which method to execute from the child class.
Therefore, Java doesn’t support multiple inheritance. The problem is commonly referred as Diamond Problem.
What is composition in Java?
Composition is again specialized form of Aggregation and we can call this as a “death” relationship. It is a strong type of Aggregation. Child object dose not have their lifecycle and if parent object deletes all child object will also be deleted. Let’s take again an example of relationship between House and rooms. House can contain multiple rooms there is no independent life of room and any room can not belongs to two different house if we delete the house room will automatically delete.
What is a Java servlet ?
What is the lifecycle of a servlet in Java?
How does cookies work in Java servlet ?