 Good morning guys so welcome back to our channel so today we are here with one more interview question that is with AT&T and this was shared by one of our subscriber friend so if you are looking out for the interview questions that are being asked at AT&T so this is the video for you and this will definitely help many others as well because this was asked to a 13 years experience candidate so I hope that this video will be helpful to all of you so let us first check the mail that we got so you see here is the mail we got this on 30th May 30 May 2021 and our subscriber friend says you guys are doing great work these are the questions that I have faced during the interview yesterday that is 29th May I have 13 years of experience please keep my identity hidden so to that we have replied thanks for sharing can you please let us know the company name so the company was AT&T so that this is about the email now let us dive into the questions that were asked to us so first we talk about the topic let us talk about the topics which were from where the questions were asked so from Kourjawa JSP springboard SQL project architecture related questions and Unix so these were the topics that were shared like that were asked and please don't forget to like this video it will definitely motivate us as well as the contributors so let us start the question so first question is what is static initializer block static initializer block static block of code inside Java class and run only one time before the constructor or main method is called so answers we have just trying to give one line answers at least so basically the questions were shared by our subscriber friend and answers we have added to it it is not the answer that was shared by the subscriber friend so these are the answers that we have added so basically one line answers so if the next question is where the static blocks get stored inside memory so basically static blocks get stored on the meta space of native heap as they are associated with the class externalization in Java what is externalization is Java so externalization is used whenever we need to customize serialization mechanism if a class implements an externalizable interface then object serialization will be done using a right external method so inside that we can say what all we want to serialize and we can exclude or whatever we don't want to serialize the next question what is heap memory in Java so simple like a heap memory is a runtime data area from which the memory of for all the classes class instances and arrays is located the heap is created when the Java about JVM basically when JVM starts up the heap memory gets created and may increase or decrease in the size while the application runs the size of the heap can be specified using hyphen XMS VM options next question what is system.gc sorry garbage collection in Java so this was the only thing that was done so basically garbage collection is the process of reclaiming the runtime unused memory automatically in other words it's a way to destroy the unused objects the next question is on the same thing which is system.gc what is system.gc or what system.gc will do so basically Java.lang.system.gc method runs the garbage collector calling this method calling this suggests that the Java virtual machine expand effort towards recycling unused objects in order to make the memory they currently occupying available for quicker use this was about the system.gc next question how to avoid deadlocks so this we have copied from one of the site that we follow so although it is not possible to avoid deadlock condition but we can avoid it by using the falling waste avoid unnecessary logs avoid nested logs using thread.join method use lock ordering lock timeout so these are the few things by using which we can eradicate a deadlock scenario but 100 percent we cannot guarantee that it will eradicate that issue coming to the next question ways to create threads so there are two ways what we say about the one is by extending the thread class and by implementing runnable interface and yes we can argue here we can use executable framework as well just we haven't written there but we can use that well so don't forget to use the Amazon link that is there in the description on your next purchase from Amazon coming to the next question can we synchronize process not thread to be honest I am also not sure on this answer if you know the answer you can comment it out what is re-entrant lock as the name says re-entrant locks allows a thread to enter into the lock on a resource more than once like more than once a system can enter into the lock basic question we can say if you work on threading you will know that use of generics in core Java so basically generics usually provide compile time type safety that allows programmers to catch in valid type set compile time itself so that is the advantage of generics what is type erasure in generics so type erasure is a process in which compiler replaces a generic parameter with an actual class or bridge method in type reassure compiler ensures that no extra classes are created and there is no runtime overhead to be honest even I don't know this I just googled the question and I got the answer what is functional interface and how it is related to lambda so basically to in a simple words lambda simplify the use of interfaces that declare single abstract method so basically lambdas get operate on functional interfaces what is of occasion like making like answer also given making jar not to decompile and how to do it so that was the question so this is not the answer related to it different between JSP include action and include directive so this is the what we could get it from the site one of the site we follow so include resources at translation time include action resource at request time better for static pages this is better for dynamic pages include the original content in generated service calls the include methods that are the differences this is related to JSP how to pass parameters from one JSP to another as far as I remember there are three ways using query parameter using hidden variables using session object if there are any other ways you can please comment what is the JSP use been so JSP use been action tag is used to locate or instantiate a bean class if bean object of a bean class is already created it doesn't create the bean depending depending on the scope but if object of the bean is not created it instantiates the bean so that is the use of use been and comes the spring what are the advantages of spring boot so there are many so pointed out few year it is very easy to develop spring based application with Java or groovy it reduces lot of development time and increases productivity it awards writing lots of boilerplate code one of the most famous advantage and removing the boilerplate code annotations and example configuration it is very easy to integrate spring boot application with spring ecosystem like spring JDBC spring ORM spring data spring security spring cloud anything it is very easy it follows of opinionated defaults configuration approach to reduce developer effort it provides embedded HTTP servers Tomcat and GT to develop and test our applications very fast and easy how say security is provided by spring boot there are to be honest there are many ways to do that or it depends from project it differs from project to project what is the default server provided by spring boot by default it uses Tomcat 7 as far as I know all this Tomcat 7 the version can be different how to change the server for 10 spring boot using you directly application dot property in the application dot property so you can directly so it says server dot port equal to whatever post you want to order or using giving arguments like hyphen d server dot port we can use both the ways we can change how to secure the rest APS there are different approaches available depending on your requirement you can choose like what is the JWT is there there are others as well so depends on the project on which you are working and what you have choose why you have choose that what is OAuth and how it functions so 1000 OAuth is an authentication protocol that allows you to approve one application interacting with another on your behalf without giving away your password so that is OAuth this is one of the way difference between controller and rest controller so that a controller is a common annotation that is used to mark a class as spring MVC controller while rest controller is a special controller used in restful web services and equivalent to controller based response body so whenever we are using at the rest controller on the controller class we don't need to specify at the right response body coming to the next question what are the what are views can we perform curd operations on views so use use is nothing but a virtual table we can create a view by joining two or more tables with or without filter criteria based on our need yes we can perform curd operations in simple view that is on single table view but if it is a complex view then we cannot perform curd operations on it what is Cartesian product so Cartesian products also referred to as a cross joint returns all the rows in all the tables listed in the query what is outdoor joint and auto join is used to return with us by combining rows from two or more tables but unlike an inner joint the outdoor joint will return every row from one specified table even if the joint condition feels differences between clustered and non clustered indexes so clustered indexes are fast non custard are slow custard indexes require less memory for operation they required more memory for operation clustered index is main data it is a call non clustered is a call works on copy of data table can have one clustered index the table can have multiple non clustered index clustered index store pointers to block non data non clustered index to both value and a pointer to actual row that holds the data so these are the differences that we could find project architecture micro services interview questions like the project was a micro micro services project was there so on that thing the questions where are so these are the four questions that were asked explain about your project architecture so I have to explain in detail about the way project architecture with respect to of your experience you have to be good at this while explaining your project because this is one of the deciding question because if you don't know about your project itself it is very hard to believe you that you have an a hands on experience encoding how request mapping is done in AWS from domain name to IP address this was the second question explain the working of functionality of Kubernetes how to load balance how do load balancers work basically load balancer divides if there are multiple instances that are running so load balancer will equally pass the traffic to both the instances or a number of instances so that load doesn't get built on only one instance this was about the micro services interview questions or project architecture interview questions next was Unix interview questions how is so these are the set of questions that are that were asked as part of Unix how is the Unix file structure how to find multiple words in multiple files at the same time how to find all words how to find the count of occurrences in group of files how to connect to linux machine inputty using same PPK file how to connect to the two systems at a time so these were the Unix interview questions so here is the mail you can see so we have you can see the entire questions we have already covered so core Java JSP Springboard SQL project architecture and Unix so you can halt through it and you can go through the mail as well so that's so that's it in this video thank you for watching I hope it will be helpful to you as well 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