Interview Questions and Answers - Order By Newest Q1621. Difference between ApplicationContext and BeanFactory ? Spring
This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  ApplicationContext  BeanFactory   ApplicationContext vs BeanFactory   frequent Q1622. What are the types of transaction management supported by Spring ? Spring
This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  spring  spring transaction management Q1623. What are the different types of advices in AOP ? Spring
This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  spring app  spring  aspect oriented programming Q1624. What is the use of upcasting in Java ? Core Java
Ans. Interfacing
Car extends Vehicle
Car car = new Car();
// now you need to call an API changeTires() which can change tires for all Vehicle Types and accepts argument of type Vehicle and hence you will have to upcast it
changeTires((Vehicle)car);
Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  upcasting  type casting Q1625. Why do we pass an array of strings to main method ? Core Java
Ans. Array of strings in the main method are the list of arguments or parameters which are sent to the application / program. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  main method   main method string array argument Q1626. In Java, what is the closest thing to pointers? Core Java
Ans. References.
Unlike pointers in C , Java references are strongly typed and we cannot do pointer arithmetics with them. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  pointers  pointers in java  references Asked in 1 Companies Q1627. In Java, would you like to see an explicit destructor? Core Java
Ans. Yes , a gc method to explicitly call garbage collection immediately on the object. It will provide better flexibility over application that require optimal usage of 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 1 Companies expert Q1628. How to calculate lcm of two numbers ? Core Java
This question was recently asked at 'HCL Tech'.This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  coding  code Asked in 1 Companies Q1629. Write a Program to find age by birth date ? Core Java
Ans. LocalDate today = LocalDate.now();
LocalDate birthday = LocalDate.of(1960, Month.JANUARY, 1);
Period p = Period.between(birthday, today); //Now access the values as below
System.out.println(period.getDays());
System.out.println(period.getMonths());
System.out.println(period.getYears()); Sample Code for LocalDate Sample Code for Period Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  coding  code  date  LocalDate  Period Asked in 1 Companies Q1630. Design a class diagram for a farm. Design
This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  class diagram   design Q1631. Explain Inheritance and Polymorphism. Core Java
Ans. Getting parent class object properties into child class is called Inheritance.
The process of representing one form into multiple forms is called polymorphism. 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  polymorphism  object oriented programming (oops)  oops concepts Asked in 1 Companies Basic   frequent Q1632. What is the difference between access and error log ? Logging
Ans. We log each access to the application resource within access logs, something like
"GET / HTTP/1.0" 200 113 "-" "Mozilla/5.0 zgrab/0.x" "-"
We log only error / warn messages within error logs, something like
ERROR 123#0: *19 connect() failed Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  logging  access log  error log Q1633. What will be the output of following code
class TestMain {
public static void main(String[] args) {
String s1 = "ravi";
String s2 = new String("ravi");
Integer i = 10;
Integer a1 = new Integer("10");
System.out.println(s1 == s1);
System.out.println(i == a1);
}
} 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  ==  coding  code Asked in 1 Companies Q1634. Will the following code compile ?
final HashMap hm = new HashMap();
hm.put("Ravi", 221); Core Java
Ans. Yes, it will compile without error. final in this context means that the reference hm cannot be assigned to a new hash map but didn't restrict from changing the state of collection already held by hm. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  final  final variable Asked in 1 Companies Q1635. Explain Java 8 concurrency mechanism. Core Java
This question was recently asked at 'IBM'.This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  synchronization  concurrency  java 8  java8 Asked in 1 Companies Q1636. What is the difference between being final and being immutable ? Are string final or immutable in Java ? Core Java
Ans. Being final in the sense of objects or object reference means that the reference cannot be reassigned to a different object whereas being immutable means that the object contents cannot be changed.
Strings in Java are immutable. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  string  immutable  immutability  final vs immutable  immutabilityAns. Graph contain cycles whereas Trees cannot. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  graph  trees  data structures  tree vs graph Q1638. What does the following initialization mean ?
ArrayList<LinkedList> traversalPaths = new ArrayList<LinkedList>();
What could be the use of such a collection. Core Java
Ans. Initialize an ArrayList that will hold LinkedLists i.e every element of the arraylist will be a linked list.
Such collection could be used in algorithms that require first random access and then sequential traversal. For example - Storing traversal paths for a graph wherein we can start from any vertex. Implementing dictionary with each arraylist element holding staring with character and then linked list holding duplicate words. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  collections  linkedlist  arraylist Q1639. What will be the output upon executing main method
public class Graph {
private static Multimap<Integer,Integer> adjacentDirectedNodesMap = ArrayListMultimap.create();
Graph(){
adjacentDirectedNodesMap.put(1, 2);
adjacentDirectedNodesMap.put(1, 3);
adjacentDirectedNodesMap.put(1, 4);
adjacentDirectedNodesMap.put(3, 5);
adjacentDirectedNodesMap.put(4, 5);
}
public static void main(String[] args){
ArrayList visited = new ArrayList();
Integer startNode = 1;
for(Integer adjacentNodes: adjacentDirectedNodesMap.get(startNode)){
System.out.println(adjacentNodes);
}
}
} Core Java
Ans. Nothing as we haven't yet created an instance and hence adjacentDirectedNodesMap won't be initialized with any value and hence is empty. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  constructor Q1640. What is the difference between return and continue statement ? Core Java
Ans. return is used within a method to return control out of the method. It may be followed by a value which is returned from the method to calling method immediately preceding the point of call.
continue statement is used within a loop to start next iteration without executing the remaining statements in the loop. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  return statement  continue statement  return vs continue  for loop  control statements  loop statement Q1641. What is the difference between return and break statement ? Core Java
Ans. return is used within a method to return control out of the method. It may be followed by a value which is returned from the method to calling method immediately preceding the point of call.
break statement is used within a loop to move control out of the loop. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  return statement  break statement  return vs break Q1642. What is the difference between Java SE Map and Apache Commons MultiMap ? How can we implement functionality similar to multimap using Java SE map ? Core Java
Ans. We can have duplicate keys within MultiMap whereas we cannot have duplicate keys within Java Util Map.
We can have a Map with value as a "collection of values" instead of single value to have a similar function as Multimap. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  Apache commons multimap  map vs multimap Q1643. What is the difference between hasNextInt and nextInt method of scanner class ? Core Java
Ans. The hasNextInt() is used to check if there are any more elements left and the nextInt() is used to access that element. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  input output  Scanner Q1644. Is it a bad practice to initialize object reference to Null ? Core Java
Ans. never initialise local to null,yes it is bad pratice Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  null  nullpointerexception Q1645. What will be the output of following code and Why ?
int x = 5;
int y = 7;
float f = 5f;
float z = y / x * f;
System.out.println(z); Core Java
Ans. 5.0
operation between two ints generate int only. so 7/5 generates 1 and not 1.4. Multiplication between int and float generates float and hence
1 * 5.0 = 5.0 Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  arithmetic calculation  data types Q1646. How do you know if a method is a constructor ? Core Java
Ans. Is the method name same as class Name - Yes
Does the method have any return type ( even void ) - No
It's a constructor Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  constructor Q1647. Is a string an array of characters in Java ? Core Java
Ans. No, String is a class whose objects are called strings in Java. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  String Q1648. Can we synchronize the run() method in Java? Core Java
This question is still unanswered. Can you please provide an answer. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  synchronization  multithreading  run method Q1649. Difference between if and switch ? Can we replace all switch statements with if statements ? Core Java
Ans. if statement is used to do 2 direction branching whereas switch is used to do multi direction branching in Java.
Yes we can replace all switch statements with nested if statements. Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  switch  if vs switchAns. if statements nested within another if or else blocks are called nested if statements.
if(condition1) {
if(condition2){
}
} Help us improve. Please let us know the company, where you were asked this question : Like Discuss Correct / Improve  if statement  control statements   nested if