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

Interview Questions and Answers for 'Ola' - 53 question(s) found - Order By Rating

Q1. What are the limitations with using interpolation ? Why do we need property binding ?

Ans. Interpolation can only work with String types and hence we need property binding while working with other data types.

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Q2. Can we use interpolation with all data types ?

^{This question is still unanswered. Can you please provide an answer.}

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Q3. What is interpolation in Angular ?

Angular

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Q4. What is SNMP ?

Networking

Ans. SNMP or Simple Network Management protocol is an application layer protocol for exchanging management information between network devices.

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Q5. How do you achieve String immutability ?

Core Java

^{This question was recently asked at 'Polaris'.This question is still unanswered. Can you please provide an answer.}

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Q6. Explain Rest architecture

Rest

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Q7. Explain memory leaks and how to prevent them.

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Q8. Difference between Query param and path param ?

^{This question was recently asked at 'GSpann Technologies, Motorola Solutions'.This question is still unanswered. Can you please provide an answer.}

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Q9. Have you heard of volatile Table in Teradata ?

Teradata

Ans. If you create table with VOLATILE option, the life of the table will be only for the current session.
It will be automatically dropped by Teradata manager once session expires.

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Q10. Can we make array volatile in Java ?

Core Java

Ans. Yes, you can make an array (both primitive and reference type array e.g. an int array and String array) volatile in Java but only changes to reference pointing to an array will be visible to all threads, not the whole array

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Q11. What are the different ways to avoid multi Threading related problems in Java ?

Core Java

Ans. Synchronization,
Concurrent classes,
Volatile keyword,
Implementing concurrent Lock interface,
Immutable classes

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Q12. how is the internal code for the "volatile" implemented ?

Core Java

^{This question was recently asked at 'Symantec'.This question is still unanswered. Can you please provide an answer.}

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Q13. Why do you want to leave your current job ?

General

Ans. The most effective and acceptable reasons for leaving your current job should be positive e.g. moving forward in your life or career

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Q14. What is your role in current project ?

General

Ans. Possible Answer - Java Developer

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Q15. Difference between Arrays and LinkedList ?

Data Structure

^{This question was recently asked at 'Spillman Technologies,Motorola Solutions'.This question is still unanswered. Can you please provide an answer.}

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Q16. Difference between JVM, JRE and JDK ?

Core Java

Ans. JDK(Java Development kit) = Development Kit comprising of JVM , library and development tools for developers

JRE (Java Run time Environment) - Comprise of JVM and set of libraries

JVM(Java Virtual Machine) = Interpreter which reads the .class file line by line.

When we install JDK, JRE also get installed so we can write,compile and excute our code. Used by developer. Without JDK we can only execute the program using JRE.

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Q17. How can i split a linked list in two parts in java 8?

Core Java

Ans. This can be done using a Spliterator.

LinkedList list = Arrays.asList("names","numbs","birds","animals");
Spliterator split1 = list.Spliterator();
Spliterator split2 = split1.Spliterator();

Now, the LinkedList is split into split1 and split2.
use split2 first then split1 to check the output.

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Q18. What is abstraction ?

Design

Ans. Abstraction is a process of hiding the implementation details and describing only the functionality to the user.

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Q19. 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.

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Q20. Explain OOPs

or

Explain OOPs Principles

or

Explain OOPs Concepts

or

Explain OOPs features

or

Tell me something about OOPs

Core Java

Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features

1. Inheritance for Code Reuse
2. Abstraction for modularity, maintenance and agility
3. Encapsulation for security and protection
4. Polymorphism for flexibility and interfacing

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Q21. Write a Program for insertion sort.

Core Java

^{This question was recently asked at 'Ola Cabs'.This question is still unanswered. Can you please provide an answer.}

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Q22. What is ConstraintViolationException in Hibernate ?

Hibernate

Ans. The exception is thrown when a database constraint is violated.

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Q23. What do you make out of this error

org.hibernate.exception.ConstraintViolationException: could not insert: [<Entity>]
Caused by: java.sql.SQLIntegrityConstraintViolationException: ORA-00001: unique constraint (<Constraint Name>) violated

and how would you go about debugging it ?

Database

Ans. Application is unable to insert a record as it violates a unique constraint.

The exception states the constraint and Table can be located by the Entity mapping. So I will go to the DB and will first check to which all columns the unique constraint applies. And then I will go and check the code and logs to see how come the duplicate column values were attempted to be inserted when they were not supposed to be.

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Q24. What is a Webdriver ?

Testing

Ans. Selenium WebDriver is a tool for automating web application testing.It helps in replicating the manual tester behavior like keyboard entry, mouse events etc and then matching the output against the expected.

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Q25. Write a program in Java that prints the numbers from 1 to 100. But for multiples of three print Fizz instead of the number and for the multiples of five print Buz. For numbers which are multiples of both three and five print FizzBuzz

Core Java

Ans. public class Class{
public static void main(String[] args){
for(int i=1;i<= 100;i++){
if(i%3 == 0){
if(i%5 == 0){
System.out.println("FizzBuzz");
}
System.out.println("Fizz");
} else if(i%5 == 0){
System.out.println("Buzz");
} else {
System.out.println(i);
}

}
}
}

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Usually asked to entry level software developers.

Q26. Write a program to swap two variables without using third

Core Java

Ans. public static void main(String[] args) {
   int num1 = 1;
   int num2 = 2;
   num1 = num1^num2;
   num2 = num1^num2;
   num1 = num1^num2;
   System.out.print("num1 = " + num1 +", num2 = "+num2);
}

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Q27. When should we use Abstract classes ?

Core Java

Ans. Abstract classes provide a mechanism of interfacing ( using abstract method ) as well as inheritance ( extending abstract class ). So they should be used in place of interfaces in case there is some code ( methods ) or object body ( member elements ) that can be reused with inheritance.

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Frequently asked in high end product companies. Frequently asked in Deloitte.

Q28. How is Hashmap internally implemented in Java ?

Core Java

Ans. https://medium.com/javarevisited/internal-working-of-hashmap-in-java-97aeac3c7beb#:~:text=HashMap%20internally%20uses%20HashTable%20implementation,the%20entries%20into%20the%20map.

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Basic and Very Frequently asked.

Q29. What is Polymorphism in Java ?

Core Java

Ans. Polymorphism means the condition of occurring in several different forms.

Polymorphism in Java is achieved in two manners

1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas

2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding.

Sample Code for overloading

Sample Code for overriding

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Q30. When do we generally get the database error - Unique Constraint Violated ?

Ans. This error can result either on an insert, update or delete when any change in data results in duplicate record or subset of it having unique constraint on record or its subset. For example - If we have a unique constraint on a combination of columns and then trying to insert duplicate column values.

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