Java Interview Question Set 8

Categories: Java 8(JDK1.8)

What is the difference between compile-time polymorphism and runtime polymorphism?

There are the following differences between compile-time polymorphism and runtime polymorphism.

SNcompile-time polymorphismRuntime polymorphism

1In compile-time polymorphism, call to a method is resolved at compile-time.In runtime polymorphism, call to an overridden method is resolved at runtime.

2It is also known as static binding, early binding, or overloading.It is also known as dynamic binding, late binding, overriding, or dynamic method dispatch.

3Overloading is a way to achieve compile-time polymorphism in which, we can define multiple methods or constructors with different signatures.Overriding is a way to achieve runtime polymorphism in which, we can redefine some particular method or variable in the derived class. By using overriding, we can give some specific implementation to the base class properties in the derived class.


What is Runtime Polymorphism?

Runtime polymorphism or dynamic method dispatch is a process in which a call to an overridden method is resolved at runtime rather than at compile-time. In this process, an overridden method is called through the reference variable of a superclass. The determination of the method to be called is based on the object being referred to by the reference variable.

class Bike{  

  void run(){System.out.println("running");}  

}  

class Splendor extends Bike{  

  void run(){System.out.println("running safely with 60km");}  

  public static void main(String args[]){  

    Bike b = new Splendor();//upcasting  

    b.run();  

  }  

}  


Can you achieve Runtime Polymorphism by data members?

No, because method overriding is used to achieve runtime polymorphism and data members cannot be overridden. We can override the member functions but not the data members. Consider the example given below.

class Bike{  

 int speedlimit=90;  

}  

class Honda3 extends Bike{  

 int speedlimit=150;  

 public static void main(String args[]){  

  Bike obj=new Honda3();  

  System.out.println(obj.speedlimit);//90  

   }  


What is the difference between static binding and dynamic binding?

In case of the static binding, the type of the object is determined at compile-time whereas, in the dynamic binding, the type of the object is determined at runtime.

Static Binding

class Dog{  

 private void eat(){System.out.println("dog is eating...");}  

  public static void main(String args[]){  

  Dog d1=new Dog();  

  d1.eat();  


 What is Java instanceOf operator?

The instanceof in Java is also known as type comparison operator because it compares the instance with type. It returns either true or false. If we apply the instanceof operator with any variable that has a null value, it returns false. Consider the following example.


class Simple1{  

 public static void main(String args[]){  

 Simple1 s=new Simple1();  

 System.out.println(s instanceof Simple1);//true  

 }  

}  


What is the abstraction?

Abstraction is a process of hiding the implementation details and showing only functionality to the user. It displays just the essential things to the user and hides the internal information, for example, sending SMS where you type the text and send the message. You don't know the internal processing about the message delivery. Abstraction enables you to focus on what the object does instead of how it does it. Abstraction lets you focus on what the object does instead of how it does it.

In Java, there are two ways to achieve the abstraction.

Abstract Class

Interface


What is the difference between abstraction and encapsulation?

Abstraction hides the implementation details whereas encapsulation wraps code and data into a single unit.


What is the abstract class?

A class that is declared as abstract is known as an abstract class. It needs to be extended and its method implemented. It cannot be instantiated. It can have abstract methods, non-abstract methods, constructors, and static methods. It can also have the final methods which will force the subclass not to change the body of the method. Consider the following example.


abstract class Bike{  

  abstract void run();  

}  

class Honda4 extends Bike{  

void run(){System.out.println("running safely");}  

public static void main(String args[]){  

 Bike obj = new Honda4();  

 obj.run();  

}  

}  


Can there be an abstract method without an abstract class?

No, if there is an abstract method in a class, that class must be abstract.


Can you use abstract and final both with a method?

No, because we need to override the abstract method to provide its implementation, whereas we can't override the final method.


 Is it possible to instantiate the abstract class?

No, the abstract class can never be instantiated even if it contains a constructor and all of its methods are implemented.

Top Blogs
Java Retention Policy, SOURCE,CLASS,RUNTIME Published at:- Meaning Of Java Published at:- Java Programming in Python Published at:- Applications of Java Programming Published at:- Java Explaination Published at:- History of Java Published at:- Tools You Will Need Published at:- Local Environment Setup Published at:- Popular Java Editors Published at:- Basic Syntax in Java Published at:- Java Identifiers Published at:- Java Modifiers Published at:- Inheritance Published at:- Object and Classes In Java Published at:- Classes in Java Published at:- Source File Declaration Rules Published at:- Java Package Published at:- Constructors Published at:- No argument Constructors Published at:- Basic Datatypes In Java Published at:- Java - Modifier Types Published at:- Java - Basic Operators Published at:- The Relational Operators Published at:- The Bitwise Operators Published at:- The Logical Operators Published at:- The Assignment Operators Published at:- Miscellaneous Operators Published at:- Precedence of Java Operators Published at:- Java - Loop Control Published at:- Java - Decision Making Published at:- Java - Numbers Class Published at:- Java In Character Class Published at:- Escape Sequences In Java Published at:- Character Methods In Java Published at:- Java In Strings Class Published at:- String Length In Java Published at:- Concatenating Strings In Java Published at:- Creating Format Strings In Java Published at:- Java - Arrays Published at:- Creating Arrays In Java Published at:- Java - Date and Time Published at:- Getting Current Date and Time Published at:- Date Comparison Published at:- Simple DateFormat Format Codes Published at:- Sleeping for a While Published at:- Gregorian Calendar Class Published at:- Java - Regular Expressions Published at:- Java - Methods Published at:- Method Calling Published at:- Passing Parameters by Value In Java Published at:- Method Overloading In Java Published at:- The finalize( ) Method In Java Published at:- Java - Files and I O Published at:- Standard Streams In Java Published at:- File Input Stream Published at:- File Output Stream In Java Published at:- Directories in Java Published at:- Java - Exceptions Published at:- Exception Hierarchy In Java Published at:- Java Programming Language Published at:- JDK in Java Published at:- History of Java Programming Language Published at:- Difference Between C++ vs Java vs Python Published at:- How JVM Works – JVM Architecture? Published at:- JVM Memory Published at:- Difference between Byte Code and Machine Code Published at:- How is Java platform independent? Published at:- Java is platform-independent but JVM is platform dependent Published at:- Java Basic Syntax Published at:- Data types in Java Published at:- Primitive data type vs. Object data type in Java with Examples Published at:- Java Identifiers Published at:- Operators in Java Published at:- Variables in Java Published at:- Types of Variables in Java Published at:- Differences between the Instance variable Vs. the Static variables Published at:- Scope of Variables In Java Published at:- Differences between JDK, JRE and JVM Published at:- Similarities and Difference between Java and C++ Published at:- Setting up the environment in Java Published at:- Packages In Java Published at:- Decision Making in Java (if, if-else, switch, break, continue, jump) Published at:- Loops in Java Published at:- Java while loop with Examples Published at:- Java do-while loop with Examples Published at:- Components of do-while Loop Published at:- Continue Statement in Java Published at:- Break statement in Java Published at:- Define Java Methods Published at:- Java Method Parameters Published at:- Return Values In JAva Published at:- Define of Java Scope Published at:- Meaning of Java Recursion Published at:- What is OOP in Java ? Published at:- Java Class Attributes Published at:- Java Class Methods Published at:- Static vs. Non-Static Java Published at:- Java Constructors Published at:- Java Encapsulation Published at:- Java Packages Published at:- Java Inheritance Published at:- Java Polymorphism Published at:- Java - Abstraction Published at:- Java - Interfaces Published at:- Declaring Interfaces In Java Published at:- Java - Overriding Published at:- Java - Packages Published at:- Java - Data Structures Published at:- Java - Data Structures Published at:- The Collection Interfaces In Java Published at:- Generics In Java Published at:- Java - Serialization Published at:- Java - Networking Published at:- Java - Sending Email Published at:- Java - Multithreading Published at:- Java - Applet Basics Published at:- Java - Documentation Comments Published at:- Comments in Java Published at:- Java Interview Questions Set 1 Published at:- Java Interview Questions Set 2 Published at:- Java Interview Questions Set 2 Published at:- Java Interview Questions Set 3 Published at:- Java Interview Questions Set 4 Published at:- Java Interview Questions Set 5 Published at:- Java Interview Questions Set 6 Published at:- Java Interview Questions Set 7 Published at:- Java Interview Questions Set 8 Published at:- Java Interview Questions Set 9 Published at:- Java Interview Question Set 10 Published at:- Java Interview Question Set 11 Published at:- Java interview Question Set 12 Published at:- Java Interview Question Set 13 Published at:- Java Interview Questions Set 10 Published at:- Java Interview Question Set 12 Published at:- Java Interview Question Set 13 Published at:- Java Interview Question Set 14 Published at:- Java Interview Question Set 15 Published at:- Java Multithreading Interview Questions Set 1 Published at:- Java multithreading interview questions Set 2 Published at:- Java multithreading interview questions Set 3 Published at:- Java Multithreading Interview Set 4 Published at:- Java multithreading interview questions Set 5 Published at:- Java collections interview questions Set 6 Published at:- Java collections interview questions Set 7 Published at:- Java Interview Question Set 8 Published at:- Java Interview Question Set 1 Published at:- Java Interview Question Set 10 Published at:- Java Interview Question Published at:- Java Interview Question Published at:- Java Interview Question Published at:- Java Interview Question Published at:- Java Interview Question Published at:- Java Interview Question Published at:- Java Interview Question Published at:- JavaScript Interview Questions Published at:- Javascript Interview Question Published at:- Javascript Interview Question Published at:- JavaScript Interview Question Set 1 Published at:- JavaScript Interview Question Set 2 Published at:- JavaScript Interview Question Set 3 Published at:- JavaScript Interview Question Set 4 Published at:- Python Interview Question Set 6 Published at:- How to Optimize Java Apps on Kubernetes Published at:- When and Why Java is utilized for Application Improvement Published at:- Scanner nextLine() ,nextInt() ,nextDouble() method in Java with Examples Published at:- java toUpperCase() and toLowerCase() example Published at:- pushing value at last in java | how to add element at the end of array in java Published at:- Write a program for group words by first character of given string | Java 8 Stream Example Published at:- Write a Java 8 program to calculate the age of a person in years given their birthday Published at:- Write a Java 8 program to calculate the age of a person in years given their birthday Years Months Days Published at:- Write a Java 8 program to print the first 10 odd numbers Published at:- Filter employees by age in Java 8 Lamda steam Published at:- Write a Java 8 program to get the last element of an array string/object Published at:- Filter employees by age set senior if age is greater than 30 in Java 8 Lamda steam Published at:- How to increment salary by 2%, 5%, etc. Using java Published at:- Write a program to find the only duplicate count list in the List Published at:- Write a program to append char in char ex-input- {A, B, C} output->[A_X, B_Y, C_Z] Published at:- Write a program to sum an array without using the sum method Published at:- Write a program to sum an array Published at:- Drop all while condition not meet dropWhile(),dropWhile(Predicate<T> predicate) Published at:- Find the maximum value in a list of integers using Stream & Method Reference Published at:- How to sort a list of strings by length using Lambda expressions Published at:- How to filter and collect a list of strings that start with a specific letter using Java 8 Stream Published at:- Write a Java program To create a map from a array of strings where the key is the string and the value is its length Published at:- How to count the number of occurrences of a given word in a list of strings using Java 8 Published at:- How to remove all duplicates from an array of integers in Java using Java 8 Published at:- How to find next, previous, tomorrow ,yesterday date using Java 8 Published at:- How to iterate and modify values in a Map using Java 8 Published at:- How to print keys & values of a Map using Java 8 Published at:- count of each character in a String using Java 8 Published at:- Write a Program to find the Maximum element in an array Published at:- How to check if list is empty in Java 8 using Optional Published at:- Find duplicate elements with its count using Java 8 Published at:- Find Last duplicate character of given string using Java 8 Published at:- Given a list of integers, separate odd and even numbers Published at:- java 8 using lambda expression and stream api | Java 8 Programs using Lambda Expression and Stream Published at:- 26 Java 8 Programs using Lambda Expression and Stream Published at:- Java 8 Stream String Null Or Empty Filter Published at:- sum ,min ,max etc example using reduce method using Java 8 Stream API Published at:- Find first repeated character in a string Published at:- Sort highest salary in each department Published at:- Grouping Employees by City and Age Published at:- Finding the Count of Male and Female Employees Published at:- Printing Names of All Departments from Employee Class using Java Published at:- Printing Employee Details by Age Criteria using Java Published at:- Finding Maximum Age of Employee using Java Published at:- Printing Average Age of Male and Female Employees using Java Published at:- Printing the Number of Employees in Each Department using Java Published at:- Java Class subclass interview coding questions Published at:- Child and Parent overridden methods Throws RuntimeException Published at:- Child and Parent overridden methods Throws checked exception Published at:- Find Customer staring with +91 mobile number Published at:- Sorting the Employees Salary in Each Department in Descending Order Published at:- Sorting the Employees Salary in Each Department in Ascending Order Published at:-
R4R.co.in Team
The content on R4R is created by expert teams.