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

Interview Questions and Answers - Order By Newest

Q1151. Write a Program for insertion sort.

^{This question was recently asked at 'Ola Cabs'.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 program code coding insertion sort sort Asked in 1 Companies}

Very frequently asked. Usually among very first few questions.

Q1152. Define encapsulation in Java ?

Core Java

Ans. Encapsulation is a feature of OOP's that binds the data and it's associated methods together as a single unit and facilitate protection and data hiding by providing minimal interface to outside. For example - member variables are declared private and are accessed through public methods. Moreover we have private methods that can only be used internally and hence providing minimal interface to outside class through use of public methods.

Sample Code for encapsulation

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve encapsulation object oriented programming (oops) oops concepts oops oops concepts oops features Asked in 4 Companies Basic frequent}

Q1153. Can an inner class be subclass of it's parent class ?

Core Java

Ans. Yes that can be done

public class OuterClass {
public class InnerClass extends OuterClass {
}
}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve inner classes nested classes sub class Basic}

Q1154. Is this code legal in java i.e nested class within interface implementing the parent interface ?

public interface MyInterface {
public class MyClass implements MyInterface {
}
}

Core Java

Ans. Yes that's legal in java

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve inner classes nested classes sub class Basic}

Q1155. What are the different types of loops in Java ?

Core Java

Ans. for, while and do while

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve loops different type of loops for loop control statements loop statement basic}

Q1156. What is an infinite loop ?

Core Java

Ans. Infinite loop is a programming condition wherein the control goes into an infinite loop because the loop termination condition can never be met. For example -

for(int x=1;x>0;x++){
}

in this loop, with each increment the condition x > 0 will remain true till infinity.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve loop infinite loop for loop control statements loop statement basic}

Q1157. Is String a Data type in Java ?

Core Java

Ans. String is not a primitive type in java. Anything defined within double quotes like "abc" is an object of String class.

Sample Code for String

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve string data type Basic}

Q1158. Are char,String and Char data types in java ?

Core Java

Ans. char is a primitive data type. String is a class. Char is a wrapper class for primitive char.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve char string data type Basic}

Q1159. Can we call a constructor for an object twice ?

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 constructor}

Q1160. Can we compile and execute a Java class without main method ?

Core Java

Ans. No without main method can not be executed it will throw an error illegal start of type. Main method is the entry point of application.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve jvm compilation main method Basic}

Q1161. Is JDK required on each machine where a Java application needs to be run ?

Core Java

Ans. No, to run application, machine needs just a JRE (Java Runtime Environment)

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve jvm jdk Basic}

Q1162. What is the purpose of re throwing the exception when we can provide the handling at the first catch itself ?

Core Java

Ans. Sometimes the calls move across layers of classes and functions and hence each layer needs to perform some function like cleaning if something goes wrong deep inside.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve exceptions exceptions handling rethrowing exception}

Q1163. What is the problem we could face if we be very liberal with importing classes even if we are not using them ? For example

import java.util.*;
import java.io.*;

Core Java

Ans. It makes application little heavy as we are importing classes that aren't required.

It creates class name conflicts as similar name classes might be available across different packages. In case of such conflicts, we will have to specify the package name with the class name at the time of it's usage.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve import statement java import}

Q1164. Which java package is loaded by default and hence doesn't require an explicit import statement ?

Core Java

Ans. java.lang

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java.lang import statement basic}

Q1165. How do we define constant variables in Java ?

Core Java

Ans. By using static and final modifiers.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve constant variables static final basic frequent}

Q1166. Can a source file contain more than one class declaration ?

Core Java

Ans. Yes, but only one of them can be declared public.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve class declaration}

Q1167. Can an interface be defined inside a class just like we can have inner classes inside a class ?

Core Java

Ans. Yes , we can have an interface that is part of a class.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve inner classes inner interface nested classes}

Q1168. Can an interface implements another interface ?

Core Java

Ans. No. No interface provides any implementation and hence the declaration isn't viable.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve interface basic}

Q1169. Why doesn't java support operator overloading ?

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 operator overloading}

Q1170. 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}

Q1171. 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}

Q1172. 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}

Q1173. 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}

Q1174. 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}

Q1175. 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}

Q1176. What is a session bean ?

Java EE

^{This question was recently asked at 'BirlaSoft'.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 session bean java bean Asked in 1 Companies}

Q1177. 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}

Q1178. 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}

Q1179. 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}

Q1180. 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}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.