The Programmer's Guide
  • About
  • Algorithm
    • Big O Notation
      • Tree
      • Problems
    • Basic Notes
    • Data Structure Implementation
      • Custom LinkedList
      • Custom Stack
      • Custom Queue
      • Custom Tree
        • Binary Tree Implementation
        • Binary Search Tree Implementation
        • Min Heap Implementation
        • Max Heap Implementation
        • Trie Implementation
      • Custom Graph
        • Adjacency List
        • Adjacency Matrix
        • Edge List
        • Bidirectional Search
    • Mathematical Algorithms
      • Problems - Set 1
      • Problems - Set 2
    • Bit Manipulation
      • Representation
      • Truth Tables
      • Number System
        • Java Program
      • Problems - Set 1
    • Searching
    • Sorting
    • Array Algorithms
    • String Algorithms
    • Tree
      • Tree Traversal Techniques
      • Tree Implementation
      • Applications of Trees
      • Problems - Set 1
    • Graph
      • Graph Traversal Techniques
      • Shortest Path Algorithms
      • Minimum Spanning Tree (MST) Algorithms
    • Dynamic Programming
      • Problems - Set 1
    • Recursion
    • Parallel Programming
    • Miscellaneous
      • Problems - Set 1
  • API
    • API Basics
      • What is an API?
      • Types of API
        • Comparison - TBU
      • Synchronous vs Asynchronous API
    • API Architecture
      • Synchronous & Asynchronous Communication
    • API Specification
  • Cloud Computing
    • Cloud Fundamentals
      • Cloud Terminology
      • Core Terminology
      • Cloud Models
      • Cloud Service Models
      • Benefits, Challenges and Risk of Cloud Computing
      • Cloud Ecosystem
  • Database
    • DBMS
      • Types of DBMS
        • Relational DBMS (RDBMS)
        • NoSQL DBMS
        • Object-Oriented DBMS (OODBMS)
        • Columnar DBMS
        • In-Memory DBMS
        • Distributed DBMS
        • Cloud-Based DBMS
        • Hierarchical DBMS
      • DBMS Architecture
      • DBMS Structure
    • SQL Databases
      • Terminology
      • RDBMS Concepts
        • Entity Relationship Diagram (ERD)
          • ERD Examples
        • Normalization
        • Denormalization
        • ACID & BASE Properties
          • ACID Properties
          • BASE Properties
        • Locking and Unlocking
      • SQL Fundamentals
        • SQL Commands
          • DDL (Data Definition Language)
          • DML (Data Manipulation Language)
          • DCL (Data Control Language)
          • TCL (Transaction Control Language)
          • DQL (Data Query Language)
        • SQL Operators
          • INTERSECT
          • EXCEPT
          • MINUS
          • IN and NOT IN
          • EXISTS and NOT EXISTS
        • SQL Clauses
          • Joins
          • OVER
          • WITH
          • CONNECT BY
          • MODEL
          • FETCH FIRST
          • KEEP
          • OFFSET with FETCH
        • SQL Functions
          • Oracle Specific
        • SQL Data Types
          • Numeric Types
          • Character Types
          • Date & Time Types
          • Large Object Types
        • Others
          • Indexing
      • Vendor Specific Concepts
        • Oracle Specific
          • Data Types
          • Character Set
          • Rownum, Rowid, Urowid
          • Order of Execution of the query
          • Keys
          • Tablespace
          • Partition
      • Best Practice
      • Resources & References
        • O’Reilly SQL Cookbook (2nd Edition)
          • 1. Retrieving Records
          • 2. Sorting Query Results
          • 3. Working with Multiple Tables
          • 4. Inserting, Updating, and Deleting
          • 5. Metadata Queries
          • 6. Working with Strings
          • 7. Working with Numbers
          • 8. Date Arithmetic
          • 9. Date Manipulation
          • 10. Working with Ranges
          • 11. Advanced Searching
          • 12. Reporting and Reshaping
          • 13. Hierarchical Queries
          • 14. Odds 'n' Ends
    • SQL vs NoSQL
    • Best Practices
  • Git
    • Commands
      • Setup and Configuration Commands
      • Getting and Creating Projects
      • Tracking Changes
      • Branching and Merging
      • Sharing and Updating Projects
      • Inspection and Comparison
      • Debugging
      • Patching
      • Stashing and Cleaning
      • Advanced Manipulations
    • Workflows
      • Branching Strategies
        • Git Flow
        • Trunk-Based Development
        • GitHub Flow
        • Comparison
      • Merge Strategies
        • Merge
        • Rebase
        • Squash
        • Fast-forward vs No-fast-forward
        • MR vs PR
      • Conflict Resolution
        • Handling Merge Conflicts
        • Merge Conflicts
        • Rebase Conflicts
        • Divergent Branches After git pull
        • Force Push
      • Patch & Recovery
        • Cherry-pick strategies
        • Revert vs Reset
        • Recover from a bad rebase
      • Rebasing Practices
        • Merge vs Rebase
        • Rebase develop branch on main branch
      • Repository Management
        • Working Directory
        • Mirror a repository
        • Convert a local folder to a Git repo
        • Backup and restore a Git repository
  • Java
    • Java Installation
    • Java Distributions
    • Java Platform Editions
      • Java SE
      • Java EE
      • Jakarta EE
      • Java ME
      • JavaFX
    • Java Overview
      • OOP Principles
        • Encapsulation
        • Inheritance
        • Polymorphism
        • Abstraction
          • Abstract Class & Method
          • Interface
            • Functional Interfaces
            • Marker Interfaces
          • Abstract Class vs Interface
      • OOP Basics
        • What is a Class?
          • Types of Classes
        • What is an Object?
          • Equals and HashCode
            • FAQ
          • Shallow Copy and Deep Copy
          • Ways to Create Object
          • Serialization & Deserialization
        • Methods & Fields
          • Method Overriding & Overloading
          • Method Signature & Header
          • Variables
        • Constructors
        • Access Modifiers
      • Parallelism & Concurrency
        • Ways to Identify Thread Concurrency or Parallelism
        • Thread Basics
          • Thread vs Process
          • Creating Threads
          • Thread Context Switching
          • Thread Lifecycle & States
          • Runnable & Callable
          • Types of Threads
          • Thread Priority
        • Thread Management & Synchronisation
          • Thread Resource Sharing
          • Thread Synchronization
            • Why is Synchronization Needed?
            • Synchronized Blocks & Methods
          • Thread Lock
            • Types of Locks
            • Intrinsic Lock (Monitor Lock)
            • Reentrant Lock
          • Semaphore
          • Thread Starvation
          • Thread Contention
          • Thread Deadlock
          • Best Practices for Avoiding Thread Issues
      • Keywords
        • this
        • super
        • Access Modifiers
      • Data Types
        • Default Values
        • Primitive Types
          • byte
          • short
          • int
          • long
          • float
          • double
          • char
          • boolean
        • Non-Primitive (Reference) Types
          • String
            • StringBuilder
            • StringBuffer
              • Problems
            • Multiline String
            • Comparison - String, StringBuilder & StringBuffer
          • Array
          • Collections
            • List
              • Array vs List
              • ArrayList
              • Vector
                • Stack
                  • Problems
              • LinkedList
            • Queue
              • PriorityQueue
              • Deque (Double-Ended Queue)
                • ArrayDeque
                • ConcurrentLinkedDeque - TBU
                • LinkedBlockingDeque - TBU
            • Map
              • HashMap
              • Hashtable
              • LinkedHashMap
              • ConcurrentHashMap
              • TreeMap
              • EnumMap
              • WeakHashMap
            • Set
              • HashSet
              • LinkedHashSet
              • TreeSet
              • EnumSet
              • ConcurrentSkipListSet
              • CopyOnWriteArraySet
        • Specialized Classes
          • BigInteger
          • BigDecimal
            • Examples
          • BitSet
          • Date and Time
            • Examples
          • Optional
          • Math
          • UUID
          • Scanner
          • Formatter
            • Examples
          • Properties
          • Regex (Pattern and Matcher)
            • Examples
          • Atomic Classes
          • Random
          • Format
            • NumberFormat
            • DateFormat
            • DecimalFormat
        • Others
          • Object
          • Enum
            • Pre-Defined Enum
            • Custom Enum
            • EnumSet and EnumMap
          • Record
          • Optional
          • System
          • Runtime
          • ProcessBuilder
          • Class
          • Void
          • Throwable
            • Error
            • Exception
              • Custom Exception Handling
              • Best Practice
            • Error vs Exception
            • StackTraceElement
    • Java Features by Version
      • How New Java Features are Released ?
      • Java Versions
        • Java 8
        • Java 9
        • Scoped Values
        • Unnamed Variables & Patterns
      • FAQ
    • Concepts
      • Set 1
        • Streams
          • flatmap
          • Collectors Utility Class
          • Problems
        • Functional Interfaces
          • Standard Built-In Interfaces
          • Custom Interfaces
        • Annotation
          • Custom Annotation
          • Meta Annotation
        • Generics
          • Covariance and Invariance
        • Asynchronous Computation
          • Future
          • CompletableFuture
          • Future v/s CompletableFuture
          • ExecutorService
            • Thread Pool
            • Types of Work Queues
            • Rejection Policies
            • ExecutorService Implementations
            • ExecutorService Usage
          • Locks, Atomic Variables, CountDownLatch, CyclicBarrier - TBU
          • Parallel Streams, Fork/Join Framework,Stream API with Parallelism - TBU
      • Set 2
        • Standards
          • ISO Standards
          • JSR
            • JSR 303, 349, 380 (Bean Validation)
        • Operator Precedence
      • Set 3
        • Date Time Formatter
        • Validation
      • Set 4
        • Input from User
        • Comparison & Ordering
          • Object Equality Check
          • Comparable and Comparator
            • Comparator Interface
          • Sorting of Objects
          • Insertion Ordering
    • Packages
      • Core Packages
        • java.lang
          • java.lang.System
          • java.lang.Thread
      • Jakarta Packages
        • jakarta.validation
        • javax.validation
      • Third-party Packages
    • Code Troubleshoot
      • Thread Dump
      • Heap Dump
    • Code Quality & Analysis
      • ArchUnit
      • Terminologies
        • Cyclic dependencies
    • Code Style
      • Naming Convention
      • Package Structure
      • Formatting
      • Comments and Documentation
      • Imports
      • Exception Handling
      • Class Structure
      • Method Guidelines
      • Page 1
      • Code Smells to Avoid
      • Lambdas and Streams Style
      • Tools
    • Tools
      • IntelliJ IDEA
        • Shortcuts for MAC
      • Apache JMeter
        • Examples
      • Thread Dump Capture
        • jstack
        • VisualVM - TBU
        • jcmd - TBU
        • JConsole - TBU
        • YourKit Java Profiler - TBU
        • Eclipse MAT - TBU
        • IntelliJ IDEA Profiler - TBU
        • AppDynamics - TBU
        • Dynatrace - TBU
        • Thread Dump Analyzers - TBU
      • Heap Dump Capture
        • jmap
        • VisualVM - TBU
        • jcmd - TBU
        • Eclipse MAT (Memory Analyzer Tool) - TBU
        • IntelliJ IDEA Profiler - TBU
        • YourKit Java Profiler - TBU
        • AppDynamics - TBU
        • Dynatrace - TBU
        • Kill -3 Command - TBU
        • jhat (Java Heap Analysis Tool) - TBU
        • JVM Options - TBU
      • Wireshark
        • Search Filters
    • Best Practices
      • Artifact and BOM Versioning
  • Maven
    • Installation
    • Local Repository & Configuration
    • Command-line Options
    • Build & Lifecycle
    • Dependency Management
      • Dependency
        • Transitive Dependency
        • Optional Dependency
      • Dependency Scope
        • Maven Lifecycle and Dependency Scope
      • Dependency Exclusions & Overrides
      • Bill of Materials (BOM)
      • Dependency Conflict Resolution
      • Dependency Tree & Analysis
      • Dependency Versioning Strategies
    • Plugins
      • Build Lifecycle Management
      • Dependency Management
      • Code Quality and Analysis
      • Documentation Generation
      • Code Generation
      • Packaging and Deployment
      • Reporting
      • Integration and Testing
      • Customization and Enhancement
        • build-helper-maven-plugin
        • properties-maven-plugin
        • ant-run plugin
        • exec-maven-plugin
        • gmavenplus-plugin
      • Performance Optimization
    • FAQs
      • Fixing Maven SSL Issues: Unable to Find Valid Certification Path
  • Spring
    • Spring Basics
      • What is Spring?
      • Why Use Spring
      • Spring Ecosystem
      • Versioning
      • Setting Up a Spring Project
    • Core Concepts
      • Spring Core
        • Dependency Injection (DI)
        • Stereotype Annotation
      • Spring Beans
        • Bean Lifecycle
        • Bean Scope
          • Singleton Bean
        • Lazy & Eager Initialization
          • Use Case of Lazy Initialization
        • BeanFactory
        • ApplicationContext
      • Spring Annotations
        • Spring Boot Specific
        • Controller Layer (Web & REST Controllers)
    • Spring Features
      • Auto Configuration
        • Spring Boot 2: spring.factories
        • Spring Boot 3: spring.factories
      • Spring Caching
        • In-Memory Caching
      • Spring AOP
        • Before Advice
        • After Returning Advice
        • After Throwing Advice
        • After (finally) Advice
        • Around Advice
      • Spring File Handling
      • Reactive Programming
        • Reactive System
        • Reactive Stream Specification
        • Project Reactor
          • Mono & Flux
      • Asynchronous Computation
        • @Async annotation
      • Spring Security
        • Authentication
          • Core Components
            • Security Filter Chain
              • HttpSecurity
              • Example
            • AuthenticationManager
            • AuthenticationProvider
            • UserDetailsService
              • UserDetails
              • PasswordEncoder
            • SecurityContext
            • SecurityContextHolder
            • GrantedAuthority
            • Security Configuration (Spring Security DSL)
          • Authentication Models
            • One-Way Authentication
            • Mutual Authentication
          • Authentication Mechanism
            • Basic Authentication
            • Form-Based Authentication
            • Token-Based Authentication (JWT)
            • OAuth2 Authentication
            • Multi-Factor Authentication (MFA)
            • SAML Authentication
            • X.509 Certificate Authentication
            • API Key Authentication
            • Remember-Me Authentication
            • Custom Authentication
          • Logout Handling
        • Authorization
        • Security Filters and Interceptors
        • CSRF
          • Real-World CSRF Attacks & Prevention
        • CORS
        • Session Management and Security
        • Best Practices
      • Spring Persistence
        • JDBC
          • JDBC Components
          • JDBC Template
          • Transaction Management
          • Best Practices in JDBC Usage
          • Datasource
            • Connection Pooling
              • HikariCP
            • Caching
        • JPA (Java Persistence API)
          • JPA Fundamentals
          • ORM Mapping Annotations
            • 1. Entity and Table Mappings
            • 2. Field/Column Mappings
            • 3. Relationship Mappings
            • 4. Inheritance Mappings
            • 5. Additional Configuration Annotations
          • Querying Data
            • JPQL
            • Criteria API
            • JPA Specification
              • Example - Employee Portal
            • Native SQL Queries
            • Named Queries
            • Query Return Types
            • Pagination & Sorting
              • Example - Employee Portal
            • Projection
          • Fetch Strategies in JPA
        • JPA Implementation
          • Hibernate
            • Properties
            • Example
        • Spring Data JPA
          • Repository Abstractions
          • Entity-to-Table Mapping
          • Derived Query Methods
        • Cross-Cutting Concerns
          • Transactions
          • Caching
          • Concurrency
        • Examples
          • Employee Portal
            • API
    • Distributed Systems & Communication
      • Distributed Scheduling
      • Inter-Service Communication
        • 1. RestTemplate
        • 2. WebClient
        • 3. OpenFeign
        • Retry Mechanism
          • @Retryable annotation
            • Example
    • Security & Data Protection
      • Encoding | Decoding
        • Types
          • Base Encoding
            • Base16 - TBD
              • Encoding and Decoding in Java - TBD
            • Base32
              • Encoding and Decoding in Java
            • Base64 -TBD
              • Encoding and Decoding in Java - TBD
          • Text Encoding - TBD
            • Extended ASCII
              • Encoding and Decoding in Java - TBD
                • ISO-8859-1
                • Windows-1252 - TBD
                • IBM Code Pages - TBD
            • ASCII
              • Encoding and Decoding in Java
        • Java Guidelines
          • Text Encoding Decoding Examples
          • Base Encoding Decoding Examples
          • Best Practices and Concepts
          • Libraries
      • Cryptography
        • Terminology
        • Java Cryptography Architecture (JCA)
        • Key Management
          • Key Generation
            • Tools and Libraries
              • OpenSSL
              • Java Keytool
                • Concept
                • Use Cases
            • Key & Certificate File Formats
          • Key Distribution
          • Key Storage
          • Key Rotation
          • Key Revocation
        • Encryption & Decryption
          • Symmetric Encryption
            • Algorithm
            • Modes of Operation
            • Examples
          • Asymmetric Encryption
            • Algorithm
            • Mode of Operation
            • Examples
    • Utilities & Libraries
      • Apache Libraries
        • Apache Camel
          • Camel Architecture
            • Camel Context
            • Camel Endpoints
            • Camel Components
            • Camel Exchange & MEP
          • Spring Dependency
          • Different Components
            • Camel SFTP
        • Apache Commons Lang
      • MapStruct Mapper
      • Utilities by Spring framework
        • FileCopyUtils
    • General Concepts
      • Spring Boot Artifact Packaging
      • Classpath and Resource Loading
      • Configuration - Mapping Properties to Java Class
      • Validations in Spring Framework
        • Jakarta Validation
          • Jakarta Bean Validation Annotations
    • Practical Guidelines
      • Spring Configuration
      • Spring Code Design
  • Software Testing
    • Software Testing Methodologies
      • Functional Testing
      • Non Functional Testing
    • Software Testing Life Cycle (STLC)
    • Integration Test
      • Dynamic Property Registration
    • Java Test Framework
      • JUnit
        • JUnit 4
          • Examples
        • JUnit 5
          • Examples
        • JUnit 4 vs JUnit 5
  • System Design
    • Foundations
      • Programming Paradigms
      • Object-Oriented Design
        • SOLID Principles
        • GRASP Principles
        • Composition
        • Aggregation
        • Association
      • Design Pattern
        • Creational Pattern
        • Structural Pattern
        • Behavioral Pattern
        • Examples
          • Data Collector
          • Payment Processor
        • Design Enhancements
          • Fluent API Design
            • Examples
    • Architectural Building Blocks
      • CAP Theorem
      • Load Balancer
        • Load Balancer Architecture
        • Load Balancing in Java Microservices
          • Client-Side Load Balancing Example
          • Server-Side Load Balancing Example
        • Load Balancer Monitoring Tool
      • Scaling
        • Vertical Scaling (Scaling Up)
        • Horizontal Scaling (Scaling Out)
        • Auto-Scaling
        • Database Scaling via Sharding
      • Caching
        • Pod-Level vs Distributed Caching
      • Networking Metrics
        • Types of Delay
        • Scenario
      • System Characteristics
      • Workload Types
      • Resilience & Failure Handling
    • Performance
      • Why Is My API Sometimes Slow ?
    • Security
      • Security by Design
      • Zero Trust Security Model
      • Zero Trust Architecture
      • Principles
        • CIA
        • Least Privilege Principle
        • Defense in Depth
      • Security Threats & Mitigations
        • OWASP
          • Top 10 Security Threats
          • Application Security Verification Standard
          • Software Assurance Maturity Model
          • Dependency Check
          • CSRFGuard
          • Cheat Sheets
          • Security Testing Guide
          • Threat Dragon
        • Threat Modeling
      • Compliance & Regulation
        • PCI DSS
    • Deployment Patterns
    • Diagrams
      • UML Diagrams
        • PlantUML
          • Class Diagram
          • Object Diagram
          • Sequence Diagram
          • Use Case Diagram
          • Activity Diagram
          • State Diagram
          • Architecture Diagram
          • Component Diagram
          • Timing Diagram
          • ER Diagram (Entity-Relationship)
          • Network Diagram
    • Common Terminologies
    • Problems
      • Reference Materials
      • Cache Design
  • Interview Guide
    • Non-Technical
      • Behavioural or Introductory Guide
      • Project Specific
    • Technical
      • Java Interview Companion
        • Java Key Concepts
          • Set 1
          • Set 2
        • Java Code Snippets
        • Java Practice Programs
          • Set 3 - Strings
          • Set 4 - Search
          • Set 5 - Streams and Collection
      • SQL Interview Companion
        • SQL Practice Problems
          • Set 1
      • Spring Interview Companion
        • Spring Key Concepts
          • Set 1 - General
          • Set 2 - Core Spring
        • Spring Code Snippets
          • JPA
      • Application Server
      • Maven
      • Containerized Application
      • Microservices
    • General
      • Applicant Tracking System (ATS)
      • Flowchart - How to Solve Coding Problem?
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  1. Interview Guide
  2. Technical

Spring Interview Companion

About

A dedicated section covering frequently asked questions from the Spring ecosystem, including Spring Boot, Spring MVC, Spring Data JPA, and more. It focuses on both theory and practical usage expected in real-world backend development interviews.

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Last updated 26 days ago

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