Interview Questions and Answers - Order By Newest Frequently asked in face to face interviews. Q991. Write a program to print fibonacci series. Core Java
Ans. int count = 15;
int[] fibonacci = new int[count];
fibonacci[0] = 0;
fibonacci[1] = 1;
for(int x=2; x < count; x++){
fibonacci[x] = fibonacci[x-1] + fibonacci[x-2];
}
for(int x=0; x< count; x++){
System.out.print(fibonacci[x] + " ");
} Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  ebay   fibonacci series Asked in 66 Companies basic   frequent Q992. Can we add more elements to an array list that has been marked as final ?
Ans. Yes, the array list can hold more elements. Final only puts the restriction that the array list reference cannot hold any other array list. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  ebay   collections   arraylist   final keyword Q993. Which Data Structure should be used for Load Balancer ?
Ans. [ Open Ended question ] Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  data structures   open ended questions   load balancer Q994. When do we generally get this database error - integrity constraint violated - parent key not found ?
Ans. This error most likely will be thrown during an insert statement, while inserting a value within a foreign key column which doesnt exist within the Parent column. For example - Trying to add a dept number reference within a Employee Table when the Dept doesnt exist in the Dept Table. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  database  integrity constraint error  integrity constraint violated Q995. What is the use of Synchronized block ? Core Java
Ans. The goal of a synchronised block is to achieve mutual exclusion i.e at one time, the segment of the code should be executed by single thread only and hence the lock needs to be retrieved before executing the segment and then released. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  synchronized block   synchronized   synchronization   multithreading   threads   mutual exclusion   concurrency Asked in 4 Companies intermediate   frequent Try 1 Question(s) Test Q996. What is continuous integration ? Process
Ans. Continuous integration or CI is the practice, of merging all developer working copies to a shared mainline several times a day. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  continuous integration   jenkins  hudson   build toolsMust know at all levels. Among Top 10 frequently asked questions in Java. Very frequently asked to fresh graduates or less experienced professionals. Ans. Its a facility for code reuse and independent extension wherein a derived class inherits the properties of parent class. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  inheritance  object oriented programming (oops)  oops concepts  oops concepts  java concepts  code reuse  code re-use   classes  derived classes Asked in 14 Companies basic   frequent Q998. What is a Java Bean ? How is it different from other Java classes ?
Ans. A Java bean is a class which abides by following conventions:
Core of the object is member elements and not operations ( methods )
Member Elements can be accessed by getters (and setters if those properties are not read-only).
serializable. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java bean   javabean   pojo   classes basic   frequent Q999. What is ADT or Abtstract Data Type ? Core Java
Ans. ADT is a container which holds different types of objects with specifications.
For example - Stack, Array, Liked list, Tree Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  data types  abstract data types Q1000. Find the repeating number using O(n) time and constant space. Algorithm
Ans. http://www.geeksforgeeks.org/find-duplicates-in-on-time-and-constant-extra-space/ Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  algorithm   program   code   coding  makemytrip.com Q1001. Write a method to convert all elements of a set to lower case. Core Java
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?keyword=Method+to+convert+all+elements+of+a+collection&category=code Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  code  coding  string  String.toLowerCase  set  collections Q1002. Write java code to Get all words from a String and display them Core Java
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?keyword=+Get+all+words+from+a+String&category=code Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  string   get all words from strings   string.splitRecently asked in Sophos Q1003. Write a Method to get a map of words and their count by passing in the string Core Java
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?keyword=Method+to+get+a+map+of+words&category=code Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  map  collections Asked in 2 Companies intermediate Q1004. Write code for singleton class Design
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?keyword=singleton+class&category=code Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  singleton  code  coding  design pattern Asked in 1 Companies Intermediate   frequent Q1005. Have you ever looked into internal implementation of Java Collections ?
Ans. Yeah, I once looked into implementation of TreeSet and TreeMap just for learning. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  collections Q1006. How is static and dynamic polymorphism achieved in Java ? Core Java
Ans. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  static polymorphism  object oriented programming (oops)  oops concepts   dynamic polymorphism  object oriented programming (oops)  oops concepts   polymorphism  object oriented programming (oops)  oops concepts   overloading   overriding   broadridg Asked in 1 Companies basic   frequent Q1007. Why can't we declare a class abstract as well as final ? Core Java
Ans. Abstract means that the class is only meant to be subclassed whereas final means that it cannot be subclassed so both concepts - abstract and final are actually mutually exclusive and hence not permitted together. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  abstract   final   java keywords Asked in 1 Companies Very frequently asked to fresh graduates. Frequently asked in NSEiT and Accenture India Q1008. Write a program to Generate prime numbers till a given number Core Java
Ans. public class Main {
public static void main(String args[]) {
int number = 2;
int count = 0;
long sum = 0;
int givenNumber = 1000;
while (count < givenNumber) {
if (isPrimeNumber(number)) {
sum = number;
count;
}
number;
}
System.out.println(sum);
}
private static boolean isPrimeNumber(int number) {
for (int i = 2; i <= number / 2; i) {
if (number % i == 0) {
return false;
}
}
return true;
}
} Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  generate prime numbers  code  coding Asked in 5 Companies basic   frequent Q1009. Write a program to calculate factorial of a number using recursion Core Java
Ans.
public class Factorial {
public static void main(String[] args){
int x = 5;
System.out.println(calculateFactorial(x));
}
private static int calculateFactorial(int x){
if(x==1){
return 1;
}
return x * calculateFactorial(x-1);
}
} Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  factorial  calculate factorial  code  coding  recursion Asked in 1 Companies basic Q1010. Write code for the usage of Builder Design Pattern
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=964 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  builder design pattern  builder pattern  code  coding intermediate Q1011. Write code for constructor overloading Core Java
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=965 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  constructor overloading  code  coding Asked in 2 Companies basic Q1012. Write code to check if an integer is odd or even using ternary operator
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=963 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  ternary operator  code  coding Q1013. Write code to sort elements of a set
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=952 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  set  collections  sorting  treeset  code  coding Q1014. In the following code , how many methods needs to be implemented in Class B ?
public interface A{
public void method1();
public void method2();
public void method3();
}
abstract class B implements A{
} Core Java
Ans. As Class B has been declared abstract , we can either implement any of these methods and just declare rest of them abstract. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  interfaces  abstract classes  code  coding Try 2 Question(s) Test Q1015. What will the following code print ?
Integer a = 100, b =100;
Integer c = 1000, d = 1000;
System.out.println(a == b);
System.out.println(c ==d); Core Java
Ans. false
false Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  object equality  code  coding   frequent Q1016. How is multiple inheritance implemented in Java ? Core Java
Ans. There was no multiple inheritance in java before version 8 as implementing multiple interfaces cannot be termed as inheritance.
With Java 8 , came the concept of default methods wherein the class implementing the interface carries the default implementation from the interface and hence facilitating multiple inheritance. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  multiple inheritance  object oriented programming (oops)  oops concepts   inheritance  object oriented programming (oops)  oops concepts   oops concept Asked in 10 Companies   frequent Q1017. Write a program for Coin Changer application ?
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=979 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  coin changer application  coin changing  general electic (ge) Q1018. What is unmodifiable set / unmodifiable map ? How can we create one ?
Ans. It is an unmodifiable / read only view of the underlying collection. We can use
Collections.unmodifiableSet(Set set)
Collections.unmodifiableMap(Map map)
Collections.unmodifiableCollection(Collection collection) Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  collections  set  unmodifiable set  map  unmodifiable map  unmodifiablemap  unmodifiableset  Collections.unmodifiableCollection  Collections.unmodifiableMap  Collections.unmodifiableSet Q1019. What is the use of MethodHandle ?
Ans. MethodHandle is a modern, more flexible, more typesafe way of doing reflection. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  MethodHandle  Reflection Q1020. What is a Destructor ? Do we have Destructors in Java ? Core Java
Ans. Destructor is used to de-allocate memory allocated by objects.
There are no destructors in Java. Alternatively, Java provides Automatic garbage collection i.e automatically releasing the un-referenced memory. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  destructor  garbage collection Asked in 11 Companies Basic   frequent Try 1 Question(s) Test