Great Learning brings you this video on Top 100 Java Interview Questions. In this video, we will take you through Top 100 most important and frequently asked Java interview questions that will help you in the near future. These questions will include the core as well as advanced topics in Java. Also, we will be covering coding questions along with a detailed explanation of the problem and how we can solve them quickly with the help of the Java Collection framework.
00:03:03 Interview questions and answers for beginners
01:41:30 Interview questions and answers for experienced users
02:21:23 Coding and tricky interview program questions and solutions
Android Interview Questions and Answers from Beginner to Advanced level
DataFlair is committed to provide you all the resources to make you an android professional. We started with android tutorials along with practicals, then we published Real-time android projects along with source code. Now, we come up with frequently asked android interview questions, which will help you in showing expertise in your next interview.
Android – one of the hottest technologies, which is having a bright future. Get ready to crack your next interview with the following android interview questions. These interview questions start with basic and cover deep concepts along with advanced topics.
1. What is Android?
Android is an open-source mobile operating system that is based on the modified versions of Linux kernel. Though it was mainly designed for smartphones, now it is being used for Tablets, Televisions, Smartwatches, and other Android wearables.
2. Who is the inventor of Android Technology?
The inventors of Android Technology are- Andry Rubin, Nick Sears, and Rich Miner.
3. What is the latest version of Android?
The latest version of Android is Android 10.0, known as Android Q. The upcoming major Android release is Android 11, which is the 18th version of Android. [Note: Keep checking the versions, it is as of June 2020.]
4. How many Android versions can you recall right now?
Till now, there are 17 versions of Android, which have their names in alphabetical order. The 18th version of Android is also going to come later this year. The versions of Android are here:
5. Explain the Android Architecture with its components.
This is a popular android developer interview question
Android Architecture consists of 5 components that are-
a. Linux Kernel: It is the foundation of the Android Architecture that resides at the lowest level. It provides the level of abstraction for hardware devices and upper layer components. Linux Kernel also provides various important hardware drivers that act as software interfaces for hardwares like camera, bluetooth, etc.
b. Native Libraries: These are the libraries for Android that are written in C/C++. These libraries are useful to build many core services like ART and HAL. It provides support for core features.
c. Android Runtime: It is an Android Runtime Environment. Android Operating System uses it during the execution of the app. It performs the translation of the application bytecode into the native instructions. The runtime environment of the device then executes these native instructions.
d. Application Framework: Application Framework provides many java classes and interfaces for app development. And it also provides various high-level services. This complete Application framework makes use of Java.
e. Applications: This is the topmost layer of Android Architecture. It provides applications for the end-user, so they can use the android device and compute the tasks.
6. What are the services that the Application framework provides?
The Android application framework has the following key services-
a. Activity Manager: It uses testing and debugging methods.
b. Content provider: It provides the data from application to other layers.
c. Resource Manager: This provides users access to resources.
d. Notification Manager: This gives notification to the users regarding actions taking place in the background.
e. View System: It is the base class for widgets, and it is also responsible for event handling.
7. What are the important features of Linux Kernel?
The important features of the Linux Kernel are as follows:
a. Power Management: Linux Kernel does power management to enhance and improve the battery life of the device.
b. Memory Management: It is useful for the maximum utilization of the available memory of the device.
c. Device Management: It includes managing all the hardware device drivers. It maximizes the utilization of the available resources.
d. Security: It ensures that no application has any such permission that it affects any other application in order to maintain security.
e. Multi-tasking: Multi-tasking provides the users the ease of doing multiple tasks at the same time.
8. What are the building blocks of an Android Application?
This is a popular android interview question for freshers.
The main components of any Android application are- Activity, Services, Content Provider, and Broadcast Receiver. You can understand them as follows:
a. Activity- It is a class that acts as the entry point representing a single screen to the user. It is like a window to show the user interface.
b. Services- Services are the longest-running component that runs in the background.
c. Content Provider- The content provider is an essential component that allows apps to share data between themselves.
d. Broadcast receivers- Broadcast receiver is another most crucial application component. It helps the apps to receive and respond to broadcast messages from the system or some other application.
9. What are the important components of Android Application?
The Components of Android application are listed below:
10. What are the widgets?
Widgets are the variations of Broadcast receivers. They are an important part of home screen customization. They often display some data and also allow users to perform actions on them. Mostly they display the app icon on the screen.
11. Can you name some types of widgets?
Mentioned below are the types of widgets-
a. Informative Widgets: These widgets show some important information. Like, the clock widget or a weather widget.
b. Collective Widgets: They are the collection of some types of elements. For example, a music widget that lets us change, skip, or forward the song.
c. Control Widgets: These widgets help us control the actions within the application through it. Like an email widget that helps check the recent mails.
d. Hybrid Widgets: Hybrid widgets are those that consist of at least two or more types of widgets.
12. What are Intents?
Intents are an important part of Android Applications. They enable communication between components of the same application as well as separate applications. The Intent signals the Android system about a certain event that has occurred.
13. Explain the types of intents briefly?
Intent is of three types that are-
a. Implicit Intents: Implicit intents are those in which there is no description of the component name but only the action.
b. Explicit Intents: In explicit intents, the target component is present by declaring the name of the component.
c. Pending Intents: These are those intents that act as a shield over the Intent objects. It covers the intent objects and grants permission to the external app components to access them.
14. What is a View?
A view is an important building block that helps in designing the user interface of the application. It can be a rectangular box or a circular shape, for example, Text View, Edit Text, Buttons, etc. Views occupy a certain area of the screen, and it is also responsible for event handling. A view is the superclass of all the graphical user interface components.
15. What do you understand by View Group?
It is the subclass of the ViewClass. It gives an invisible container to hold layouts or views. You can understand view groups as special views that are capable of holding other views, that are Child View.
16. What do you understand about Shared Preferences?
It is a simple mechanism for data storage in Android. In this, there is no need to create files, and using APIs, it stores the data in XML files. It stores the data in the pair of key-values. SharedPreferences class lets the user save the values and retrieve them when required. Using SharedPreferences we can save primitive data like- boolean, float, integer, string and long.
17. What is a Notification?
A notification is just like a message that shows up outside the Application UI to provide reminders to the users. They remind the user about a message received, or some other timely information from the app.
18. Give names of Notification types.
There are three types of notifications namely-
a. Toast Notification- This notification is the one that fades away sometime after it pops up.
b. Status Notification- This notification stays till the user takes some action on it.
c. Dialog Notification- This notification is the result of an Active Activity.
19. What are fragments?
A fragment is a part of the complete user interface. These are present in Activity, and an activity can have one or more fragments at the same time. We can reuse a fragment in multiple activities as well.
20. What are the types of fragments?
There are three types of fragments that are: Single Fragment, List Fragment, Fragment Transactions.
21. What are Layout XML files?
Layout XML files contain the structure for the user interface of the application. The XML file also contains various different layouts and views, and they also specify various GUI components that are there in Activity or fragments.
22. What are Resources in Android Application?
The resources in Android Apps defines images, texts, strings, colors, etc. Everything in resources directory is referenced in the source code of the app so that we can use them.
23. Can you develop Android Apps with languages other than Java? If so, name some.
Yes, there are many languages that we can work with, for the development of Android Applications. To name some, I would say Java, Python, C, C++, Kotlin, C#, Corona/LUA.
24. What are the states of the Activity Lifecycle?
Activity lifecycle has the following four stages-
a. Running State: As soon as the activity starts, it is the first state.
b. Paused State: When some other activity starts without closing the previous one, the running activity turns into the Paused state.
c. Resume State: When the activity opens again after being in pause state, it comes into the Resume State.
d. Stopped State: When the user closes the application or stops using it, the activity goes to the Stopped state.
25. What are some methods of Activity?
The methods of Activity are as follows:
26. How can you launch an activity in Android?
We launch an activity using Intents. For this we need to use intent as follows:
27. What is the service lifecycle?
There are two states of a service that are-
a. Started State: This is when the service starts its execution. A Services come in start state only through the startService() method.
b. Bounded State: A service is in the bounded state when it calls the method bindService().
28. What are some methods of Services?
The methods of service are as follows-
29. What are the types of Broadcast?
Broadcasts are of two types that are-
a. Ordered Broadcast: Ordered broadcasts are Synchronous and work in a proper order. It decides the order by using the priority assigned to the broadcasts.
b. Normal Broadcast: These are asynchronous and unordered. They are more efficient as they run unorderly and all at once. But, they lack full utilization of the results.
30. What are useful impotent folders in Android?
The impotent folders in an Android application are-
31. What are the important files for Android Application when working on Android Studio?
This is an important android studio interview question
There are following three files that we need to work on for an application to work-
a. The AndroidManifest.xml file: It has all the information about the application.
b. The MainActivity.java file: It is the app file that actually gets converted to the dalvik executable and runs the application. It is written in java.
c. The Activity_main.xml file: It is the layout file that is available in the res/layout directory. It is another mostly used file while developing the application.
32. Which database do you use for Android Application development?
The database that we use for Android Applications is SQLite. It is because SQLite is lightweight and specially developed for Android Apps. SQLite works the same way as SQL using the same commands.
33. Tell us some features of Android OS.
The best features of Android include-
34. Why did you learn Android development?
Learning Android Studio is a good idea because of the following-
35. What are the different ways of storage supported in Android?
The various storage ways supported in Android are as follows:
36. What are layouts?
Layout is nothing but arrangements of elements on the device screen. These elements can be images, tests, videos, anything. They basically define the structure of the Android user interface to make it user friendly.
37. How many layout types are there?
The type of layouts used in Android Apps are as follows:
38. What is an APK?
An APK stands for Android Package that is a file format of Android Applications. Android OS uses this package for the distribution and installation of the Android Application.
39. What is an Android Manifest file?
The manifest file describes all the essential information about the project application for build tools, Android operating system, and google play. This file is a must for every Android project that we develop, and it is present in the root of the project source set.
#android tutorials #android basic interview questions #android basic questions #android developer interview questions #android interview question and answer #android interview questions #android interview questions for experienced #android interview questions for fresher
offers powerful features for the rapid development of deployment-ready applications. It is the most used and best java framework for the development of scalable microservices and web applications.
If you want to become a domain expert, you have come to the right place. We have curated some the most repeatedly asked spring boot interview questions and answers to help you ace the interview.
#full stack development #interview question answer #spring boot interview questions answer #top spring boot interview questions #top 10 critical spring boot interview questions #answers
OpenJDk or Open Java Development Kit is a free, open-source framework of the Java Platform, Standard Edition (or Java SE). It contains the virtual machine, the Java Class Library, and the Java compiler. The difference between the Oracle OpenJDK and Oracle JDK is that OpenJDK is a source code reference point for the open-source model. Simultaneously, the Oracle JDK is a continuation or advanced model of the OpenJDK, which is not open source and requires a license to use.
In this article, we will be installing OpenJDK on Centos 8.
#tutorials #alternatives #centos #centos 8 #configuration #dnf #frameworks #java #java development kit #java ee #java environment variables #java framework #java jdk #java jre #java platform #java sdk #java se #jdk #jre #open java development kit #open source #openjdk #openjdk 11 #openjdk 8 #openjdk runtime environment
Hello guys, Java Collection and Generic are a very important topic for Java Interviews. They also present some of the hardest questions to a programmer when it comes to interviews, especially Generics.
It’s not easy to first understand what a particular piece of code doing with those question marks and other signs and then the pressure of interviews also makes it hard to answer complex usage of Generics.
But, with proper preparation and paying attention to both Java Collection and Generic, you can solve that hurdle. If you are looking for Java job but haven’t done well in the interviews you have given so far then you have come to the right place.
In this article, I have shared a lot of Java interview questions on various topics and difficulty levels.
There are Java questions for beginners as well as expert programmers. They are theoretical questions based upon Java programming concepts as well as coding and data structure algorithms questions for programmers, and this article is only going to make that collection even more valuable.
In this article, I am going to share some of the frequently asked Java Collection and Generic questions from Interviews. These are the questions you have often seen on a telephonic round of Java interview as well as on face-to-face interviews.
It’s useful for both beginners having 2 to 3 years of experience as well as experienced Java programmers with 5 to 6 years of experience.
This list has a collection of questions which has both easy and tough questions in it but the most important thing is that most of the questions have already been asked on interviews. I am sure you might have also seen it in your interviews.
knowing the answers to these questions will not only help you to crack your Java interview but also understand Java Generics and Collection topic in-depth, which will eventually help you to write better Java programmers and code.
Btw, if you are new to Java or want to solidify your Java knowledge then you should check out a comprehensive course like The Complete Java Masterclass before attempting to solve these questions. It will help you immensely by filling gaps in your knowledge and going back and forth. It’s also the most up-to-date course and covers every new feature introduced in new Java releases
Without wasting any more of your time, here is my list of 50+ Java interview questions on Collection and Generics.
If you have done some work in Java +then you should know the answer to these questions but if you don’t you can always see the answer.
Instead of writing answers here, I have linked them to relevant posts so that you can try to solve the problem by yourself here and if you need you can get an in-depth discussion on individual posts to learn the topic in depth.
1) What is the Java Collection Framework and How do you choose different collections? (answer)
Here is the diagram which answers this question:
2) What are Generics in Java? (answer)
hint: Java feature to ensure type safety at compile time.
3) Which are your favorites classes from Java Collection Framework? (answer)
4) When do you use Set, List, and Map in Java? (answer)
hint — use set when you don’t need duplicates, use List when you need order with duplicates, and use Map when you need to store key-value pair.
5) Which Sorted Collection have you used? (answer)
hint — TreeSet is one example of a sorted Collection
6) How HashSet works in Java? (answer)
hint — same as HashMap, using hashing and equals() and hashCode() method. HashSet is actually backed by HashMap where keys are elements you store in HashSet and values are always null.
**7) Which two methods you should override for an Object to be used as a key in hash-based Collections? **(answer)
hint — equals and hashcode
**8) Can you use HashMap in a concurrent application? **(answer)
hint — Yes, but only if you are reading from the HashMap and its initialized by a single thread, otherwise no.
**9) What is the difference between HashMap and Hashtable in Java? **(answer)
hint — HashMap is fast but not threadsafe, Hashtable is slow but thread-safe
** 10) What is the difference between synchronized and concurrent Collection in Java? (answer)**
11) How ConcurrentHashMap works in Java? (answer)
partitions map into segments and lock them individually instead of locking the whole map.
12) What is PriorityQueue in Java? (answer)
A data structure that always keeps the highest or lowest element at the head so that you can access or remove it in constant time.
**13) What is type-erasure in Generics? **(answer)
Its a part of Java compiler which removes all type related information after compilation from Java so that the generated code is the same as before Generics.
** 14) What is the difference between ArrayList and Vector in Java? (answer)**
hint — ArrayList is not synchronized hence fast, Vector is synchronized hence slow
15) What is the difference between LinkedList and ArrayList in Java? (answer)
hint — ArrayList is backed by array while LinkedList is backed by a linked list which means search with index is only possible in ArrayList.
** 16) What is the difference between Hashtable and ConcurrentHashMap in Java? (answer)**
hint — ConcurrentHashMap is a new concurrent class with better scalability as only a portion of the map called segment is locked while Hashtable is an old class where the whole map is Locke for synchronization. Seet **Java Collections: Fundamentals **course for more details.
17) What is the difference between LinkedHashSet and TreeSet in Java? (answer)
TreeSetis a sorted set where elements are stored in their natural or custom sorting order depending upon comparable and comparator while LinkedHashSet is just an ordered collection that maintains insertion order.
#java #interview #java interview #interview-questions
40 Spring questions and answers to prepare for your next interview.
The Spring framework makes J2EE (Java 2 Platform Enterprise Edition) development easier and is used to create testable, high performing, reusable code. Spring is commonly applied in the information technologies and financial sector due to its modularity and dependency injection features.
Financial technology is an exciting and evolving field for developers who want to work at companies like MIT, Accenture, or Visa, which prefer Spring over Java EE. These companies are looking for developers like you with Spring Framework experience to help digitize their enterprise needs.
But, how do you know if you’re ready for an interview? And how do you prepare?
Today, we’ll go through a study guide of the top 40 Spring interview questions to make sure you’re ready to ace your Spring Framework interview.
Here’s what we’ll cover today:
#spring boot #j2ee #spring framework #interview questions #enterprise java #interview preparation #coding interview question #enterprise java beans #java beans #spring boot framework