Java concepts to brush up before going for interview

1) Core java
1)  JVM  Architcture
2)  Java Memory Management 
3)  Garbage Collection
4)  String comparison(==,equals method), String pool, why String        immutable, String in HashMap
5)  Oops(Polymorphism,Abstraction, Encapsulation, Inheritance)
6)  SOLID principles
7)  static & final & finalize & finally
8)  Immutability and implementation

9)  Exception Handliing (types checked, unchecked, in       polymorphism context)

10) Autoboxing, Unboxing & Wropper classes
11) Serialization, Serial Version UID
12) Multhithreading (Thread creation, producer Consumer problem inter thread comm, local thread, volatile, synchronization)
13) Concurrency (Thread pool, Executor Service, countdown latch, cyclic barier, callable vs Runnable.)
14) Collection(List, Set, Map implementations and internal implementation)
15) comparator vs comparable
16) Java 8 (Function programming, Lambdas, stream api, Date api)
17) equals vs hashcode methods
18) Basic programms


2) Design Patterns
1)  Creational
1) Singlton
2) Factory
3) Abstrct Factory

2)  Structural
1) Adopter
2) Composite
3) Proxy

3)  Behaviaral
1) Template
2) Observer
3) Stratagy

3) Security
1) Spring security
2) Oauth 2
3) JWT


4) Data Structures
1) Arrays(1 and 2 dimentinal)
2) Stack(LIFO)
3) Queue(FIFO)
4) Linked List(Singly & Doubly), find the middle element, check is double
5) Hash Table (Hasing technique
6) Trees(Binary trees, tree traversal)
7) Graphs

5) Algorithems
1) Arrays (find number, find duplicate, 2 numbers sum given number, prime number without 2 loops, String combinations,...)
2) Searching
3) Sorting

6) Spring
1) Spring IOC
2) Spring AOP
3) Spring MVC
4) Spring Rest
5) Spring ORM,JDBC
6) Spring Boot
7) Spring Could
8) Spring Transction mgmt

7) WebServices
 1) Diff b/w Rest vs Soap
1) Restful
2) Soap

8) Microservices
1) Monolithic Vs Microservices
2) Advantages & Disadvantages
3) How to monitor microservices
 4) where do you store logs in microservice
5) Can you define microservices
6) Steps that need to take to convert monolithic project to microservice
7) Communication between service


9) Hibernate
1) pros and cons over jdbc
2) load vs get , lazy loading and proxy
3) Mappings like association and Inheritence mapping(oneToOne, OneToMany, ManyToMany)
4) Cache
5) commit vs flush
6) Transaction
7) Object states

10) SQL
1) sql DDL 
2) DML queries
3) Sql constraints (Unique, Primary, composit primary..)
4) Agrigate functions
5) Group by & Having & Order By
6) Row Num vs Rank Vs DensRank
7) Partition
8) Normalization
9) pivote

11) NoSql
1) MongoDB ( sql vs Nosql, Why/When we need to use nosql)

12) Messaging
1) ActiveMq (Queue, Topic)
2) JMS ( OneToOne, OneToMany pub sub)
3) Kafka (Kafka Cluster, Prtition, replica, incync replica)