Interview Questions and Answers - Order By Newest Q1111. 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 Q1112. 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 Q1113. 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 Q1114. 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 Q1115. Write a program / method to input few numbers and then print the sum.
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=946 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  code  coding  scanner basic Very frequently asked to fresh graduates. Frequently asked in NSEiT and Accenture India Q1116. 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 Q1117. 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 Q1118. 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 Q1119. 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 Q1120. 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 Q1121. 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 Q1122. 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 Q1123. 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 Q1124. 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 Q1125. 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) Q1126. What are the new classes in JDK 1.9 ( Java 9 ) ?
Ans. http://www.buggybread.com/2015/05/java-9-new-classes-and-interfaces-in.html Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  java9  java 9  jdk1.9  jdk 1.9 Q1127. 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 Q1128. 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 Q1129. 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 Q1130. What are JSP Scriptlets?
Ans. Scriptlet allow to write Java code inside JSP like following
<% Java Code %> Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  jsp  jsp scriptlet  scriptlet Q1131. What is struts.devMode?
Ans. The struts.devMode is used to make sure that framework is running in development mode or production mode by setting true or false. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  struts  struts.devMode Q1132. What is use of Revert in SVN? Tools
Ans. Revert your local changes.
There are 2 types of reverts -
1) Local Revert: It will delete all changes from files which you made after updates and before commit.
2) Repo Revert: Upload the changes to previous Repo. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  svn  subversion  version control system  configuration management Asked in 2 Companies Q1133. Can we have multiple threads consuming message stream from a single partition ?
Ans. Yes, by having multiple Consumer Groups. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  apache kafka  kafka  kafka consumer  kafka topic partitions  bigdata  consumer group Q1134. Can we have multiple threads consuming messages from a single partition if we have single Consumer Group ?
Ans. No, we can only have max 1 thread per partition in a single Consumer Group. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  apache kafka  kafka  kafka consumer  kafka topic partitions  bigdata  consumer group Q1135. If we have more threads than partitions in a kafka consumer, How can we model it efficiently ?
Ans. We will have to use multiple consumer groups in that case as threads will remain idle if we use single consumer group. A more sophisticated algorithm could be required with multiple groups if we have to ensure the order of consumption. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  apache kafka  kafka  kafka consumer  kafka topic partitions  bigdata  consumer group Q1136. Is Iterator a class ?
Ans. No, iterator is an interface that is used to parse through the elements of a Collection Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  collections  iterator Q1137. Can a lock be acquired on a class? How is it different than the object level lock ?
Ans. Yes, a lock can be acquired on the class. Class level lock is applicable on the whole class and hence on all objects of the class whereas the object level lock is applicable on the respective object. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  synchronization  class level lock  object level lock Q1138. Difference between Yielding and Sleeping ?
Ans. When a task invokes its yield method, it returns to the ready state. When a task invokes its sleep method, it returns to the waiting state. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  multithreading  threads  yielding  sleeping  thread states Q1139. What is the use of Runtime Class ?
Ans. This class is used to provide access to the Java runtime system Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  runtime class  jre  java runtimeFrequently asked. Q1140. What should a class do if its implementing an interface ? Core Java
Ans. It should either implement all interface methods or declare unimplemented methods as abstract. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  interfaces Asked in 1 Companies Basic   frequent Try 1 Question(s) Test