Tech-zadu

Micro Services

How to create springboot app:

1.Using spring cli
2. https://start.spring.io/
3.Maven and dependencys

RestTemplate resttemplate = new RestTemplate();

resttemplate.getForObject(Stirng Url, Object out put Class);

Creating Bean in Spring boot

In Main method of spring

@SpringBootApplication
public Main class{

@Bean
public RestTemplate getRestTemplate(){
return new RestTemplate();
}

public void main method{
}

}

in Controller

@Autowired
RestTemplate reasttemplate;

resttemplate.getForObject()

Webclient vs Resttemplate

Webclint: Async requests
Resttemplate: sync request

to handle web urls we have service discovery concept

client <----> service discovery <-----> service 1, service 2, service 3

download euraka server from start.spring.io.

and put dependency as Euraka Server

need to add below dependency for client and version

<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>
and in properties add
<spring-cloud.version>Greenwich.SR3</spring-cloud.version>

and add applicatoin name in application.properties.
spring.application.name=testapp

how to to discover the servec url

on @RestTemplate use @LoadBalanced keyword and in the resttemplate url use application.name value to discover

Example

service application name->RBAC-SERVICE

resttemplate.getForObject("http://RBAC-SERVICE/getpermissions")

Expose localhost to the Internet with public URL

Signup at ngrok.com and run the below command

Command: ngrok.exe http 8080

Collections

Collection:

A group of individual objects called as collection.

Why do we need collections in java?

Array are not in dynamic nature. Once array size is defined we cannot modify the size and add the elements. A new array must be created with bigger sized and all the elements need to be copied to the new array.

Collection are used in situation where data is dynamic. Collection have default methods for search, sort…etc. so programmer no need to write functions.

Overview:

interface Collection<E> extends Iterable<E>{

}

interface List<E> extends Collection<E>{

//Only care about position of the object

//Elements can be added with specifying the index

//If position is not specified element will be added at the end of the list.

}

interface Set<E> extends Collections<E>{

//Unique things only - No duplicates allowed

//if obj.equals(obj2) than only one object will be available

}

interface Queue<E> extends Collection<E>{

//Arranged in a order of processing

}

Interface Map<K,v>{

//Contains key value pairs

//things with unique keys.

}

What are the methods declared in Collection interface

interface Collection<E> extends Iterabale<E>{

boolean add (E e);

boolean remove (Object o);

int size();

boolean isEmpty();

void clear();

boolean contains(Object o);

boolean containsAll(Collection<?> c)

boolean addAll(Collection<?> c)

boolean removeAll(Collection<?> c)

boolean retainAll(Collection c)

Iterator<E> iterator();

}

Explain about List interface

Interface List<E> extends Collection<E>{

boolean addAll(int position , Collection c)

E get(int index)

E set(int index, Object E)

Void add(int position, Object E)

E remove(int index)

Int indexOf(Object O)

Int lastIndexOf(Object o)

}

Class ArrayList { /* implements List<E>, RandomAccess*/

//Implements RandomAccess, a market interface , means it supports faster fetching

//insertion and deletion is slower comparing to LinkedList

}

Class vector{/* implements List<E>, Random Access */

//Implements Random Access- a market interface, means its supports faster fetching

//Thread Safe – Synchronised

}

Class LinkedList{ /* Implements List<E>, Queue */

//Elements are doubly linked list – means forward and backwards – to one another

// Ideal choice to implement stack or queue

//Fast insertion and deletion

//Implements Queue interface so supports methods of pop, poll, remove

}

Interface Set<E> extends Collection<E>{

//unique things only

//if obj1.equals(obj2) then only one object will be available in set

}

//maintains elements in sorted order

Interface SortedSet<E> extends collectin<E>{

SortedSet<E> subset(E fromElement, E toElement)

SortedSet<E> tailSet(E fromElement)

SortedSet<E> headset(E toElement)

E first()

E last()

}

Interface NavigableSet<E> extends SortedSet<E>{

E lower(E)

E floor(E)

E higher(E)

E ceiling(E)

E pollFirst()

E pollLast()

}

Class HashSet { /* implemnts set */

//unorderd, unsorted – iteraterates in random order

//uses hashCode

}

Class LinkedHashSet { /* Implemnts Set */

//order – iterates in insertion order

//unsorted

//uses hashCode

}

Class TreeSet{ /* implements navigableSet */

//sorted – natural order

//implements navigableset

}

Set/Hashset implementation:

Jira

1. Why Jira?

Jira is basically an issue & Project tracking toll which allows us to track any project related work by following proper workflow.

i) 1.able to track Project Progress

ii) 2.Users Project Management & bug Tracking feature implementation

2. What is Referred as issues in Jira?

Any bug or Error

New Software Task

Resolving Ticket

Request processed from

3. What type of charts we have in Jira?

Pie charts

Time Tracking

Resolution Time

User Work load

Resolved Vs Created Issues

4. What does clining issue means?

It is the process of creating duplicate issue with original one in order to assign the issue to multiple users to resolve.

5. How can you track time spent on issues ?

Blue Color - Estimated Time

Orange color - Remaining time to resolve

Green Color - Total Time to Resolve

Java Multi Threading

Java Multi Threading

1.Introduction
2.how many ways to define the thread
by extending the thread class
by implementing runnable interface
3. setting and getting name of threads
4.Thread priorites
5.the methods to prevent thread execution
yield
join
sleep
6. Synchronization
7.Internal Thread Communication
8. Dead lock
9. Demon Threads
10.Multi Threading Enhancements

Multi Tasking
categorized into two types
1.process based( where each task is different task and executed separately )
2. Thread based( where single task is executed independently as process)

2. Defining a thread

We can define a thread 2 wasys.
1.by extending a thread the thread class.

class mythread extends Thread{
public void run(){
sop ("child cthread")
}
}

p s v main(){
mythred t = new mythread(); // instantiation
t.start(); // starting a thread

}

difference b/w t.start & t.run
t.start(): a seperated flow will be created.
t.run(): normal call as function

2.by implementing runnable interface.

Thread.start() internal implementation
1.thread schedular will register the thread
2. perferorm all other mandatory formalties
3.invoke run methdod

DOA Questions

Reverse First K elements of Queue

put k elements in stack->s and poll the elements from queue->q.
take size of stack in variable size
add stack elements into queue

public Queue<Integer> modifyQueue(Queue<Integer> q, int k)
{
Stack<Integer> stack = new Stack<>();
int count = k;
while (count > 0) {
stack.push(q.poll());
count--;
}
int size = q.size();
while (!stack.empty()) {
q.add(stack.pop());
}

while(size > 0) {
q.add(q.poll());
size--;
}

return q;
}

GIT Source versioning System

Git: Source versioning System

GitHub, Gitlab & Bitbucket are service providers for version Control

GitHub: Public and Open Source
GitLab: Private & to use for Organization

Git Commands:

Version: $git --version
Set User Name: $ git config --global user.name = "Lavakush"
Get User Name: $ git config --global user.name
Get all Global Config list: $ git config --global --list
Check out Master: $ git checkout master
Pull latest changes: $ git pull origin master -u
Create Branch: $ git checkout -b "branch name"
Check the changes: $ git status
Add all files: $git add *
Store the changes : $ git commit -m "comment"
push the changes to remote repo: $ git push -u origin master

How GIT Works

Git is repository is a key-value object store all objects are indexed by SHA-1 hash value.
All commits & commented files different type of objects living in repository.
A git is large Hash table with no provision made for hash collection.
Git specifically works by taking shortstops of files

LIST OF COMMANDS:-

1. Help

$ git help

2. Get help from help of config

$ git help config

3. Configure name

$ git config –global user.name= “Lavakush”

4. Configure email

$ git config –global user.email=Lokesh.nbp@gmail.com

5. Initiate git

$ git init

6. Add a file

$ git add filename.txt

7. To commit

$git commit -m “Comment”

8. To check the history of commits

$ git log

9. Different ways to add the add command and files

$ git add –all

$ git add “*.txt”

$ git add folder /

$ git add folder/*.txt

10. Check changes from last commit

$ git diff

11. To undo staging of the file add in staging

$ git reset head licence

12. Undo last commit & bring file to staging

$ git reset -soft HEAD ^

13. Undo last commit & remove from staging

$ git rest -hard HEAD ^

14. To remove last 2 commits

$ git reset -hard HEAD ^^

15. REMOTE ADDRESS

$ git remote add origin “URL”

$ git push -u origin master

$ git clone URL

BRANCH

16. Create Branch

$ git branch testing

17. list all the branches

$ git branch

18. Check out a branch

$ git checkout testing

19. To merge testing branch with master

$git merge testing

20. Delete branch

$ git branch -d testing

21. PULL VS FETCH

Git pull = Git Fetch + Git Merge

22. What is git Stash

If we are in middle of some task and need to jump to another task we use stash

23. STAGING AREA OR INDEX

Is before competing the commits, it can formatted & reviewed in intermediate area known as Staging Area or Index

24. Git ARCHITECHTURE

How to uninstall SQL server 2014 on windows

How to uninstall SQL Server Management Studio:

This step-by-step article describes how to uninstall the Microsoft SQL Server Management Studio tools. You may have to uninstall these tools if you receive the following error message:

Setup has detected a version of SQL Server Management Studio on this machine. SQL Server Management Studio and SQL Server Management Studio Express cannot be installed on the same machine. To install SQL Server Management Studio Express, you must first uninstall SQL Server Management Studio, and then, rerun SQL Server Management Studio Express Edition Setup. For more information, see article 909953 in the Microsoft Knowledge Base.

Check here with video step-by-step instructions
Click here

Inter View Questions

How many ways can we create object?

5 Ways we can create object in java
i)using new keyword
Test t = new Test();

ii) using clone method
Test t = new test();
Test t2 = (Test) t.clone();

iii)Class.ForName();
Class c = Class.forName("nameOfTheClass");
Test t = c.newInstance();

iv)Desensitization concept
FileInpputStream f = new FileInputStream("filepath");
ObjectInputStream o = new ObjectInputStream(f);
Object o = (Test) o.readObject();

V) Using newInstance() method of constructor
Constroctor<Test> c = Test.class.getDeclaredConstrocter();
Test t = c.newInstance();

Methods in object class?
Implementation of contact list in mobile and searching algorithm?
Which one is good to implement array list or HashMap and why?
Write down deep cloning program.
How to secure the RESTFUL webservices?
Find the defect coin out of 72 coins in minimum steps using weighing scale.
Write the program to find the max two product of a array with least time complexity. { 1,2,46,64,,43,3} output-> 64*43.
Write a program to find the circular HashMap.
How many ways we can send data from client?
I want to send data as json format by GET request.How can I do?
In how many ways I can send data in RESTFUL?
How will u handle content of data send by client when u dony know which type of data client will send?
I wanna build application without any xml file in spring fw ,how can I do?
If I don’t wanna use xml then what are the ways to configure DispatcherServlet,Controller,HandlerMapping,View Reslver?
What is path parameter & query parameter & matrix parameter? If I wanna send 2 query parameter in same url on different path segment then how u will do?
How will u do form handling data in RESTFUL?
Difference between spring 4 & 3
What is dfference between @Path ,@RequestMapping()?
In RESTFUL IF I don’t wanna configure the ServletContainer in web.xml then what are the other options we can use?
What is IOC container?
What is setter & constructor injection? How will u implement it in ur spring application?
Like RESTFUL we have @Path for handling the request ,if we create a servlet application then we can use @WebServlet for handling request uri, so can I call servlet also as RESTFUL?
WHAT IS bean lifecycle?
What is beanpostprocessor?
What all types of hamdler mapping & use cases?
What types ofview resolver, controller & use cases?
Spring mvc flow?
How many approaches we have for using spring JDBC?
HOW TO USE SPRING with Hibernate application?do spring provide hibernate related stuff for integrating it?
Java 8 features?
Concurrent collection?
Executor framework?
If I wanna use 2 databases at the same time in spring then what should I do?
Difference between jdbc,hibernate?
Pls write hibernate configuration file for MSSQL server database?
What is DIALECT in hibernate?
What is use of hbm2ddl.auto?
What is SESSIONFACTORY in hibernate?
How to use 2 database in hibernate in same congiguration? Is it possible? If not then how to implement it?
If we don’t wanna configuration file in hibernate then how can we implwmnet hibernate ?
What is mapping file in hibernate ?
What are the annotation u used in hibernate ?
What are inheritance mapping in hibernate?
What is relationship in hibernate
What is difference between get & load?
Difference between save & persist?
Difference between update & merge?
What is criteria in hibernate?
What is named query in hibernate?
What is hql in hibernate ?
Write hql for selecting all record from employee table
Write hql for selecting id,name from employee table?

About Me

G'day, I'm Lavakush.

I'm a seasoned web developer who does'nt belive in taking shortcuts.

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