Java Advanced Interview Knowledge Point Summary!

1. Common Design Patterns

Singleton mode: Lazy, a hungry man, double check lock, static load, internal class loading, enumeration class loading. Ensure that a class has only one instance and provides a global access point to access it.

Proxy mode: Dynamic agent and static proxy, when to use dynamic proxy.

Adapter mode: Transforms the interface of a class into another interface that the customer wants. The adapter mode makes it possible for those classes that would otherwise not work together because of incompatible interfaces to work together.

Decorator Mode: Dynamically adds functionality to the class.

Observer pattern: sometimes referred to as the Publish/subscribe pattern, the Observer pattern defines a one-to-many dependency that allows multiple observer objects to listen to a Subject object at the same time. This subject object notifies all observer objects when the state changes, enabling them to automatically update themselves.

Policy mode: Define a series of algorithms, encapsulate them one by one, and make them interchangeable with each other.

Appearance mode: Provides a consistent interface for a set of interfaces in a subsystem, and the appearance pattern defines a high-level interface that makes this subsystem easier to use.

Command mode: Encapsulates a request into an object, allowing you to parameterize the customer with different requests.

Creator mode: Separates a complex build from its presentation so that the same build process can create different representations.

Abstract Factory mode: Provides an interface to create a series of related or interdependent objects without specifying their specific classes.

2. Basic knowledge

Java basic type which, the occupied byte and the range

The differences and connections between Set, List, and map

When to use HashMap

When to use Linkedhashmap, Concurrenthashmap, Weakhashmap

Which collection classes are thread-safe

Why set, List, map do not implement cloneable and serializable interfaces

Implementation of the CONCURRENTHASHMAP, 1.7 and 1.8

The realization of Arrays.sort

When to use Copyonarraylist

Use of volatile

Use of synchronied

The difference between the realization of Reentrantlock and synchronied

The principles and problems of CAS implementation

The realization principle of AQS

What is the difference between an interface and an abstract class, and when to use

The steps of the class loading mechanism, what to do with each step, the loading time of static and final modified member variables

Parental delegation Model

Reflection mechanism: Reflection dynamic Erase Generics, reflection dynamic call method, etc.

Dynamic binding: Parent class reference to child class object

JVM Memory management mechanism: what are the areas and what each region does

JVM garbage collection mechanism: garbage collection algorithm garbage collector garbage Collection policy

JVM parameter settings and JVM tuning

What happens when a young generation of memory overflows, and what happens when an old generation of memory overflows

Inner classes: Use and distinction of static inner classes and anonymous inner classes

Redis and memcached: When to choose Redis, when to choose memcached, what are the memory models and storage policies?

MySQL basic operations master-slave database consistency Maintenance

What are the optimization strategies for MySQL?

MySQL index implementation principle of B + Tree

What happens when the index is not hit and causes a full table scan

The difference and connection between bio NiO Aio in Java

Why bio is blocked NiO non-blocking NIO is what the model is

The overall architecture of Java IO and the design patterns used

Reactor model and Proactor model

Structure and content of HTTP request messages

HTTP three-time handshake and four-time wave

RPC Related: How to design an RPC framework that is integrated into the IO Model Transfer Protocol serialization approach

Linux command stats, sorting, previous questions, etc.

Stringbuff and StringBuilder implementations, the underlying implementation is achieved through the byte data, plus the copy of the array

Use of CAS operations

Synchronous implementation of memory cache and database consistency

Advantages and disadvantages of micro-services

Parameter issues for thread pools

IP issues How to tell if IP is in multiple IP segments

Determines whether the sum of any two numbers in an array of two is a given value

The realization of optimistic lock and pessimistic lock

Synchronized Implementation principle

The difficulties you encounter in the project and how to solve them

The highlights that you've done in the project are better

Differences between Message Queuing broadcast mode and publish/Subscribe mode

Producer Consumer Code implementation

Deadlock Code Implementation

Thread pool: parameters, the role of each parameter, the comparison of several different thread pools, the use of blocking queues, the denial policy

Future and Listenablefuture asynchronous callbacks related

Algorithm correlation: Determine whether to find out two numbers from the array and for the given value, randomly generated 1~10000 do not repeat and put into the array, the maximum and the sub-array of the array, the realization of the binary search algorithm and time complex calculation

3. Other

Algorithms: Common sorting algorithms, binary lookup, linked list correlation, array correlation, string correlation, tree correlation, etc.

Common serialization protocols and their pros and cons

Memcached memory principle, why block-based storage

What needs to be prepared to build an RPC

If the on-line server frequently appears full GC, how to troubleshoot

If a moment on the line machine suddenly changed a lot, service can't carry, how to solve

Implementation of Lur algorithm

Linkedhashmap Implement LRU

Define the data structure of the stack, implement a min function that can find the minimum stack element in the type

The solution of mass data processing

Evolution of the reactor model

Blocking, non-blocking, synchronous, asynchronous differences

Collection sub-interface

JVM Tuning Related

Zookeeper correlation, node type, how to implement service discovery and service registration

Nginx Load Balancer Related, let you to achieve load balance, how to implement

Linux commands, awk, cat, sort, cut, grep, Uniq, WC, top, etc.

Pressure test correlation, how to analyze, single-Interface pressure measurement and multi-case pressure measurement

What do you think you are a bit of what your shortcomings are

The implementation principle of spring MVC

Netty Bottom implementation, IO Model, channelpipeline implementation and principle

Design and optimization of the cache

Cache and database consistency synchronization solutions

Your project's system architecture, talk about the overall implementation

Usage scenarios for Message Queuing

The difference between ActiveMQ, RabbitMQ and Kafka

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Java Advanced Interview Knowledge Point Summary!