Javas
DB Interview Questions
Databases What is a “database”? What is a “database management system”? What is a “relational data model”? Define the terms “simple”, “composite”, “candidate”, and “alternate” key. What is a “primary key”? What are the criteria for its selection? What is a “foreign key”? What is “normalization”? What normal forms exist? What is “denormalization”? What is it applied for? What types of relationships exist in a database? Provide examples. What are “indexes”?
Understanding Unit Testing and Integration Testing
Explore the differences between unit testing and integration testing, including their definitions, key concepts, and more.
Understanding Servlets, JSP, and JSTL for Interview Preparation
An extensive guide on Servlets, JSP, and JSTL with common interview questions and answers.
Understanding the JVM
JVM What Does the JVM Do? Classloader Runtime Data Areas Frames Execution Engine Useful Links What Does the JVM Do? Loads, verifies, and executes bytecode; Provides a runtime environment for executing bytecode; Manages memory and performs garbage collection; The Java Virtual Machine (JVM) is a mechanism that provides a runtime environment for managing Java code or applications. It is an independent execution shell for code, enabling it to run on any operating system without the operating system affecting the executing program.
Interview Questions for Java 8
Interview Questions for Java 8 What new features were introduced in Java 8 and JDK 8? What is a “lambda”? What is the structure and unique characteristics of using a lambda expression? What variables can lambda expressions access? How can you sort a list of strings using a lambda expression? What is a “method reference”? What types of method references do you know? Explain the expression System.out::println. What are “functional interfaces”?
JDBC Interview Questions
JDBC What is JDBC? What are the advantages of using JDBC? What is a JDBC URL? What components make up JDBC? List the main classes and interfaces in JDBC. Describe the main steps for working with the database using JDBC. List the main data types used in JDBC. How are they related to Java types? How do you register a JDBC driver? How do you establish a connection to a database?
Understanding Serialization in Java
A comprehensive guide to understanding serialization in Java, including key concepts and best practices.
Understanding XML: Key Concepts and Definitions
Learn the fundamentals of XML, including what XML, DTD, XSD, and namespaces are, and their importance in web development and data representation.
Java Collections Framework
Interview Questions Java Collections Framework What is a “collection”? Name the main interfaces of the JCF and their implementations. Arrange the following interfaces in a hierarchy: List, Set, Map, SortedSet, SortedMap, Collection, Iterable, Iterator, NavigableSet, NavigableMap. Why is Map not a Collection, while List and Set are Collection? What is the difference between java.util.Collection and java.util.Collections? What is “fail-fast behavior”? What is the difference between fail-fast and fail-safe? Provide examples of iterators that implement fail-safe behavior.
Basics of CSS
Basics of CSS What is «CSS»? How are comments denoted in CSS? What is a «selector»? List the main types of selectors. What is a pseudo-class? What attribute selectors are there? What is the difference between #my and .my? What is the difference between margin and padding? What is the difference between the values 0 and auto in the margin property? Which property sets the background color? How to remove the underline from all links on the page?
Basics of HTML
Interview Questions Basics of HTML What is «HTML»? What is «XHTML»? What is DOCTYPE and why is it needed? What is the purpose of the <head> tag? What is the difference between <div> and <span>? How are comments denoted in HTML? How is the address of a document specified for linking? How to create a link to an email address? What is the purpose of the <em> tag? What are the purposes of the <ol>, <ul>, <li> tags?
Design Patterns
Design Patterns What is a “design pattern”? Name the main characteristics of design patterns. Types of design patterns. Provide examples of main design patterns. Provide examples of creational design patterns. Provide examples of structural design patterns. Provide examples of behavioral design patterns. What is an “anti-pattern”? What anti-patterns do you know? What is Dependency Injection? What is a “design pattern”? A design pattern is a proven and ready-to-use solution. It is not a class or a library that can be plugged into a project; it’s something more than that – it is language-independent, not a finished example that can be directly converted into code, and it can be implemented in different ways across various programming languages.
Input/Output Streams in Java
Input/Output Streams in Java What is the difference between IO and NIO? What NIO features do you know? What are “channels”? What types of input/output streams exist? Name the main classes of input/output streams. In which packages are the classes for input/output streams located? What subclasses of the InputStream class do you know, and what are they for? What is PushbackInputStream used for? What is SequenceInputStream used for? Which class allows reading data from an input byte stream in the format of primitive data types?
Interview Questions
Interview Questions OOP What is OOP? Name the main principles of OOP. What is _“encapsulation”? What is _“inheritance”? What is _“polymorphism”? What is _“abstraction”? What does “message passing” represent? Describe the basic concepts of OOP: “class”, “object”, “interface”. What are the advantages and disadvantages of the object-oriented approach in programming? What do the expressions “is” and “has” imply in the context of OOP principles? What is the difference between composition and aggregation?
Java Concurrency Interview Questions
Interview Questions Multithreading Tell us about the Java memory model? What is “thread safety”? What is the difference between “concurrency” and “parallelism”? What is “cooperative multitasking”? What type of multitasking does Java use? What is the reasoning behind this choice? What are ordering, as-if-serial semantics, sequential consistency, visibility, atomicity, happens-before, mutual exclusion, safe publication? What is the difference between a process and a thread? What are “green threads,” and does Java have them?
Java Core Interview Questions
Interview Questions Java Core What are the differences between JRE, JVM, and JDK? What access modifiers exist? What does the final keyword indicate? What are the default values for uninitialized variables? What do you know about the main() function? What logical operations and operators do you know? What is the ternary conditional operator? What bitwise operations do you know? Where and for what is the abstract modifier used? Define the term “interface”.
Logging
Interview Questions Interview Questions Logging What types of logs exist? What are the components of the log4j logging system? What is a Logger in log4j? What is an Appender in log4j? What is a Layout in log4j? List the logging levels in log4j. What is their priority order? What configuration methods exist for log4j? What types of logs exist? System; Security; Application (Business). A user logs into the application, and their password is verified.
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Java Developer Interview Questions This guide provides a comprehensive list of questions commonly asked during Java developer interviews, covering a wide range of topics from OOP principles to multithreading, JDBC, and web development.