Interview Questions and Answers for 'Java' | Search Interview Question

Interview Questions and Answers - Order By Newest

Q761. Which of the following do you think is the primary reason you would never use a static class even the application doesn't need multiple requests or threads ?

a. Serialization
b. Runtime Polymorphism
c. Lazy Loading
d. Memory

Ans. Runtime Polymorphism

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Rarely asked as it was introduced with Java 8.

Q762. Which keyword specify that a variable is effectively final ? a. final b. No Keyword c. Both of the above d. None of the above

Core Java

Ans. No Keyword

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Rarely asked as it was introduced with Java 8.

Q763. Which of the following has been introduced with Java 8 ? a. StringBuffer b. StringBuilder c. StringFilter d. StringJoiner

Core Java

Ans. StringJoiner

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Q764. Which is the Parent Class of CertStoreParameters class?

Ans. Clonable

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Q765. Are Servlet classes Thread Safe ?

Java EE

Ans. No

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Q766. Develop a simple paint like program using applets ?

Ans. Follow the below steps:

1- import the required class and packages.
2- create a class Drawtest for creating an applet.
3- initialize panles and controls int the init() method.
4- Define the destroy() method to destroy the same.
5- create an instance for draw test class and call the init(0 and start() methods in the main method)).
6- Add a new frame to the applet window and resize it to 300x300.
7- Declare a method get applet infor to display the applet information.
8- Declare two constants LINES , POINTS which are going to be the modes.
9- Define the paint method and perfoem the required operations.
10- Display the result according to the mode selected.

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Q767. Explain Application / Server architecture being used in your project ?

or

Explain your project architecture ?

Ans. We are using cluster of Web servers and Application servers. Load Balancer is used to manage the load between them. Down the layer we have middleware server and then DB server to access database.

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Q768. Have you ever faced any problem due to caching?

Ans. Yes , sometime we receive issues related to outdated pages being rendered to the user. In those cases we clear the cache and then try to investigate the reason for that. Sometime the issue is due to comparatively high refresh interval. In those cases we reduce the cache refresh interval.

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Q769. Will a for loop like following throw a compilation error ? for(;;);

Ans. No. It will result in infinite loop

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Q770. What is GregorianCalendar class ?

Ans. This class provides support for traditional Western calendars.

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Q771. What is a ResourceBundle Class ?

Ans. This class is used to store locale specific resources that can be loaded by a program to tailor it to the particular locale.

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Q772. Difference between prefix and postfix increment operator ?

Ans. Prefix operator performs the increment and then assignment whereas its inverse for postfix operator.

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Q773. What are fail-fast Iterators ?

Core Java

Ans. Fail-fast iterators detect illegal concurrent modification during iteration and fail quickly and cleanly rather than risking arbitrary, non deterministic behavior at an undetermined time in future. Example could be of an Iterator failing if it smells ConcurrentModificationException.

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Q774. Print natural numbers sequentially with two threads.

Core Java

Ans. http://stackoverflow.com/questions/18799591/print-natural-sequence-with-help-of-2-threads1-is-printing-even-and-2nd-is-pri

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Frequently asked in face to face interviews.

Q775. 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] + " ");
}

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Q776. 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.

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Must know at all levels. Among Top 10 frequently asked questions in Java. Very frequently asked to fresh graduates or less experienced professionals.

Q777. What is Inheritance ?

Core Java

Ans. Its a facility for code reuse and independent extension wherein a derived class inherits the properties of parent class.

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Q778. 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.

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Q779. 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

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Q780. 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

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Q781. 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

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Q782. 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

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Q783. 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.

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Q784. 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.

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Very frequently asked to fresh graduates. Frequently asked in NSEiT and Accenture India

Q785. 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;
}
}

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Q786. 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);
   }
}

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Q787. Write code for constructor overloading

Core Java

Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=965

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Q788. 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.

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Q789. 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

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Q790. 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.

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