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

Interview Questions and Answers for 'Visa' - 7 question(s) found - Order By Rating

Q1. Design Parking Lot.

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Q2. Explain OAuth.

Authentication

Ans. OAuth is an open-standard authorization protocol or framework that describes how unrelated servers and services can safely allow authenticated access to their assets without actually sharing the initial, related, single logon credential. Like using Google or Facebook to login to something.

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This question can be asked in different variants like performace improvement of an application, improving performance for DB communication etc.

Q3. What are the ways in which execution time of the code can be improved ?

Solution

Ans. This depends on entirely upon the code type. For example

1.If its just logic, we can try it to short circuit or put the if / switch case with maximum probability in the beginning.

2. Can use faster data structures, for eg - random retrieval instead of sequence / iterator

3. Working with primitive types or even bytes instead of Objects, even though it may result in marginal improvement.

4. If its service call, then service call with bulk load can help

5. If DB Operation, then with use of Indices , Views or using ORM , cache etc.

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Q4. Explain static blocks in Java ?

Core Java

Ans. A static initialization block is a normal block of code enclosed in braces, { }, and preceded by the static keyword. Here is an example:

static {
// whatever code is needed for initialization goes here
}

A class can have any number of static initialization blocks, and they can appear anywhere in the class body. The runtime system guarantees that static initialization blocks are called in the order that they appear in the source code.

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Q5. Advantage of Collection classes over Arrays ?

Core Java

Ans. Collections are re-sizable in nature. We can increase or decrease the size as per recruitment.
Collections can hold both homogeneous and heterogeneous data's.
Every collection follows some standard data structures.
Collection provides many useful built in methods for traversing,sorting and search.

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Very Frequently asked. Favorite question in walkins and telephonic interviews. Usually among first few questions. Asked in different variants. Must know for intermediate and expert professionals.Among Top 10 frequently asked questions.

Q6. What is rule regarding overriding equals and hashCode method ?

Core Java

Ans. A Class must override the hashCode method if its overriding the equals method.

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Q7. Can we have null keys in TreeMap ?

Core Java

Ans. No, results in exception.

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