Interview Questions.

Question 1. What Is Inheritance In Java?

Answer :

Inheritance is an Object orientated feature which lets in a class to inherit behavior and records from different class. For example, a class Car can enlarge fundamental feature of Vehicle magnificence with the aid of the usage of Inheritance. One of the most intuitive examples of Inheritance inside the actual world is Father-Son relationship, where Son inherit Father's assets. If you do not know, Inheritance is the short manner to turn out to be wealthy.

Question 2. Why Multiple Inheritance Is Not Supported By Java?

Answer :

Java is introduced after C++ and Java designer did not need to take some C++ feature that's difficult and no longer essential. They think more than one inheritances is one among them which would not justify complexity and confusion it introduces. You can also test why multiple inheritances are not supported in Java for more reasons and discussion around this.

Adv Java Interview Questions
Question 3. Why Inheritance Is Used By Java Programmers?

Answer :

Inheritance is used for code reuse and leveraging Polymorphism by way of developing a kind hierarchy. It's better to use Inheritance for kind declaration however for code reuse composition is a better alternative as it's extra bendy. See this text for learning extra approximately why Composition is higher than Inheritance.

Question 4. How To Use Inheritance In Java?

Answer :

You can use Inheritance in Java via extending classes and implementing interfaces. Java provides two key phrases extends and implements to gain inheritance.  A magnificence that's derived from some other elegance is called a subclass and an interface that is derived from another interface is known as subinterface. A class which implements an interface is referred to as implementation.

Adv Java Tutorial
Question 5. What Is The Syntax Of Inheritance?

Answer :

You can use both extends of implements keyword to put in force Inheritance in Java.  A elegance extends some other elegance using extends key-word, an interface can make bigger every other interface the usage of expand keyword, and a category can enforce an interface using implements key-word in Java.

J2EE Interview Questions
Question 6. What Is The Difference Between Inheritance And Encapsulation?

Answer :

Inheritance is an item orientated concept which creates a figure-baby dating. It is one of the ways to reuse the code written for parent elegance however it also bureaucracy the premise of Polymorphism. On the other hand, Encapsulation is an item orientated concept that is used to hide the inner information of a class e.G. HashMap encapsulate the way to shop elements and the way to calculate hash values.

Question 7. What Is The Difference Between Polymorphism And Inheritance?

Answer :

Both Polymorphism and Inheritance is going hand reachable, they assist each other to obtain their intention. Polymorphism allows flexibility, you could pick out which code to run at runtime through overriding.  See the precise answer for extra details.

J2EE Tutorial Core Java Interview Questions
Question eight. Can We Override Static Method In Java?

Answer :

No, you can't override a static technique in Java as it's resolved at compile time. In order for overriding to paintings, a method need to be digital and resolved at runtime because gadgets are simplest available at runtime. This is one of the intricate Java questions, in which interviewer tries to confuse you. A programmer is never positive approximately whether they can override or overload a static method in Java.

Question nine. Can We Overload A Static Method In Java?

Answer :

Yes, you can not overload a static approach in Java. Overloading has not anything to do with runtime however the signature of every method need to be one of a kind. In Java, to trade the technique signature, you have to alternate either quantity of arguments, type of arguments or order of arguments.

JSP Interview Questions
Question 10. Can We Override A Private Method In Java?

Answer :

No,  you can not override a private approach in Java due to the fact the non-public approach isn't inherited by the subclass in Java, that is vital for overriding. In fact, a private method isn't visible to anybody outside the magnificence and, greater importantly, a name to the non-public approach is resolved at collect time through the use of Type records rather than runtime by way of using the real item.

Core Java Tutorial
Question 11. What Is Method Hiding In Java?

Answer :

Since the static approach can not be overridden in Java, however if you claim the same static approach in subclass then that could conceal the technique from the superclass. It means, if you name that technique from subclass then the only in the subclass could be invoked but in case you call the identical approach from superclass then the only in superclass might be invoked. This is known as method hiding in Java.

Java-Springs Interview Questions
Question 12. Can A Class Implement More Than One Interface In Java?

Answer :

Yes, A magnificence can enforce a couple of interface in Java e.G. A magnificence can be both Comparable and Serializable on the identical time. This is why the interface must be the best use for defining Type as described in Effective Java. This characteristic permits one class to play a polymorphic role inside the program.

Adv Java Interview Questions
Question 13. Can A Class Extends More Than One Class In Java?

Answer :

No, a category can simplest enlarge simply one extra class in Java. Through Every class additionally, through default make bigger the java.Lang.Object magnificence in Java.

JSP Tutorial
Question 14. Can An Interface Extends More Than One Interface In Java?

Answer :

Yes, unlike instructions, an interface can amplify multiple interface in Java. There are numerous instance of this behavior in JDK itself e.G. Java.Util.List interface extends each Collection and Iterable interface to inform that it's far a Collection as properly because it permits iteration thru Iterator.

Question 15. What Will Happen If A Class Extends Two Interfaces And They Both Have A Method With Same Name And Signature?

Answer :

In this case, a struggle will get up because the compiler will not capable of link a way call due to ambiguity. You will get a collect time errors in Java.

JMS(Java Message Service) Interview Questions
Question 16. What Is The Liskov Substitution Principle?

Answer :

The Liskov substitution precept is one of the 5 object-oriented layout concepts, together realize as SOLID concepts. This design principle is L of SOLID acronym. The Liskov substitution precept states that in an item oriented software if a feature or approach is expecting an item of base class then  it must work pleasant with a derived elegance item as properly. If it can't function well with derived elegance item then the derived magnificence is violating the Liskov Substitution precept.
For example, if a technique is watching for a List you may also skip ArrayList or LinkedList and it must work just nice because ArrayList and LinkedList both comply with Liskov Substitution Principle, but the java.Sq..Date which is a subclass of java.Util.Date in Java violates Liskov Substitution Principle because you cannot bypass an item of java.Sq..Date class to a way which is looking ahead to an object of java.Util.Date, Why? Because all time-associated approach will throw java.Lang.UnsupportedOperationException.
Here is some other instance of violating The Liskov Substitution Principle, Square is a unique sort of Rectangle whose adjacent sides are same but making Square extending Rectangle violates LSP precept. For extra info on SOLID layout ideas, study Clean Code by way of Rober C. Martin, the inventor of SOLID ideas.
Java-Springs Tutorial
Question 17. How To Call A Method Of A Subclass, If You Are Holding An Object Of The Subclass In A Reference Variable Of Type Superclass?

Answer :

You can call a technique of the subclass by way of first casting the item keep through reference variable of  superclass into the subclass. Once you preserve the object in subclass reference type, you may name methods from the subclass. See how type casting works in Java for more info.
That's all about a few correct interview questions based totally OOP idea,  Inheritance. You should also realize that how personal and final variables affect Inheritance. How can you amplify a class that's maintaining a private variable, and probably the distinction between private and protected modifier in Java? They are simply important to apprehend and use Inheritance in Java.
Also, if you suppose we've got overlooked any crucial question associated with Inheritance o If you encounter any exact questions based upon Inheritance or other object oriented idea then please percentage with us.
Java applet Interview Questions