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

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Q1501. Name few classes that are part of java.io package ?

Ans. http://www.buggybread.com/2015/01/java-javaio-classes-and-interfaces.html

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Rarely asked as it was introduced with Java 8.

Q1502. What are the changes in Java.io in Java 8 ?

Core Java

Ans. http://www.buggybread.com/2015/01/migrating-to-java-8-new-classes_62.html

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Q1503. Name few classes that are part of java.lang package ?

Ans. http://www.buggybread.com/2015/01/java-javalang-classes-and-interfaces.html

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Q1504. Name few classes that are part of java.util package ?

Ans. http://www.buggybread.com/2015/01/java-javautil-classes-and-interfaces.html

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Q1505. Name few Java util classes that were introduced with Java 7 ?

Ans. http://www.buggybread.com/2015/01/migrating-to-java-7-new-classes_25.html

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Q1506. Name few Java Util classes introduced with Java 8 ?

Core Java

Ans. http://www.buggybread.com/2015/01/migrating-to-java-8-new-classes_25.html

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Rarely asked as it was introduced with Java 8.

Q1507. Name few java.lang classes introduced with Java 8 ?

Core Java

Ans. http://www.buggybread.com/2015/01/migrating-to-java-8-new-classes.html

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Q1508. How to make sure that a string contains only Numerals ?

Core Java

Ans. We can use NumberUtils.isNumber which is a part of apache commons package.

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Q1509. What is Jenkins ?

Jenkins

Ans. It is a continuous integration tool written in Java.

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Q1510. Which SCM tools Jenkins supports ?

Jenkins

Ans. AccuRev, CVS, Subversion, Git, Mercurial, Perforce, Clearcase and RTC

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Q1511. What are the various ways in which build can be scheduled in Jenkins ?

Jenkins

Ans. Builds can be triggered by source code management commits.
Can be triggered after completion of other builds.
Can be scheduled to run at specified time ( crons )
Manual Build Requests

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Q1512. What is the relation between hudson and Jenkins ?

Jenkins

Ans. Hudson was the earlier version of current Jenkins. After some issue , the project name was changed from Hudson to Jenkins.

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Q1513. What you do to make sure that your project doesn't break in Jenkins ?

Jenkins

Ans. I make sure that I perform successful clean install on my local machine with all unit tests.
Then I make sure that I check in all code changes.
Then I do a Synchronize with repository to make sure that all required config and POM changes and any difference is checked into the repository.

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Q1514. What you do when you see a broken build for your project in Jenkins ?

Jenkins

Ans. I will open the console output for the build and will try to see if any file changes were missed.
If not able to find the issue that way, Will clean and update my local workspace to replicate the problem on my local and will try to solve it.

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Q1515. Should we have instance variables in the Spring Bean which has been scoped as Singleton ?

Spring

Ans. No, if required we should only have final variables.Bean scoped singleton means that only one instance of the bean will be created and will be shared among different requests and hence instance variables will get shared too.

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Q1516. What is the difference between Fisheye and Crucible ?

Ans. FishEye is used to extract information from source code repository whereas Crucible is used to request, perform and manage code reviews.

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Q1517. Can we use Fisheye and Crucible independently ?

Ans. Yes

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Q1518. What does the red and green line backgrounds denotes in the crucible code Review ?

Ans. Red Background for a line denotes the lines that have been deleted with the change set and Green background denotes the addition.

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Q1519. What is atlassian Jira ?

Ans. Jira is a Issue / Ticket Management system developed by atlassian. It assists in Defect Management , Issue Management and Project Management.

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Frequently asked in Tata Consultancy (TCS) interview ( Based on 2 Feedback )

Q1520. What are the technologies used in Jira ?

Tools

Ans. JIRA is written in Java and uses the Pico IOC container,Apache OFBiz entity engine, and WebWork technology stack. For remote procedure calls (RPC), JIRA supports REST, SOAP, and XML RPC.

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Q1521. Which are SCM's can be integrated with Jira ?

Ans. Clearcase, CVS, Git, Mercurial, Perforce, Subversion and Team Foundation Server

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Q1522. What are the different types of boards in Jira ?

Ans. Scrum boards are for teams that plan their work in Sprints.

Kanban boards are for teams that focus on managing and constraining unplanned work.

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Q1523. What is a Board in Jira ?

Ans. We need a board to work with issues in JIRA Agile. A Board can display issues from one or more projects.

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Q1524. What is Jira Workflow ?

Ans. A JIRA workflow is the set of statuses and transitions that an issue goes through during its lifecycle.

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Q1525. What is the Jira workflow used in your project ?

Ans. We are using the following workflow with the following Issue states

Open -> Assigned -> In Progress -> QA -> Resolved -> Closed

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Q1526. What are stateless objects ? How are they different from immutable objects ? Which of these two is thread safe ?

Object Oriented Programming

Ans. Stateless objects are the objects without instance fields (instance variables). The class may have compile time constants i.e static final fields.Immutable objects are the objects which have state but the state cannot be changed after initialization. Both are Thread safe.

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Q1527. What are advantages of stateless and / or immutable objects ?

Object Oriented Programming

Ans. They can be shared across multiple threads as they are thread safe.

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Q1528. What are the advantages and disadvantages of static variables and static methods ?

Core Java

Ans. Advantages

Can do meta object operations ( like validating something before creating objects , keep count of number of objects )

Can do operations which have nothing to do with objects but still you want them to be tied to Class.

Disadvantages

Commonly used to static variables sometime leads to problems due to access by different objects.

Are not tied to objects so doesn't reflect pure Object Oriented approach.

Needs to be synchronized so as to avoid update conflicts by mutiple objects and threads.

Some limitation in testing as not all frameworks have facility to mock them. Powermock has but Mockito doesnt

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Q1529. Write code explaining use of Scanner class ?

Ans. Scanner sc = new Scanner(System.in);
int i = sc.nextInt();

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Q1530. Write program for input: I am a boy, output: I1 am2 a1 boy3?

Ans. public static void main (String args[]) {
String inputStr = "I am a boy, output: I1 am2 a1 boy3";

String splitStr[] = inputStr.split(" ");

String outputStr = new String();

for(String str1: splitStr){
outputStr += str1 + str1.length() + " ";
}

System.out.println(outputStr);
}

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