Shulou(Shulou.com)06/02 Report--

This article mainly introduces "what are the contents of learning the Java language". In the daily operation, I believe that many people have doubts about learning the content of the Java language. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the questions of "what is the content of learning the Java language?" Next, please follow the editor to study!

1. Java skill tree 1. Basic grammar

This includes the role of keywords such as static, final, transient, the principle of the foreach loop, and so on. For example, when the interviewer asks you what the static keyword does, if you answer the static modification variable, the modification method, the interviewer will think you are qualified, answer the static block, you will think you are good, answer the static internal class will think you are very good, answer the static guide package will be very satisfied with you, because you can see that you are very keen on research technology.

2. Set

The collection needs to master the implementation principles of ArrayList, LinkedList, Hashtable, HashMap, ConcurrentHashMap, and HashSet. Of course, it is better to master the CopyOnWrite container and Queue.

We also need to understand the lock segmentation technology of ConcurrentHashMap, whether the read of ConcurrentHashMap should be locked, and why, whether the iterator of ConcurrentHashMap is a strong consistent iterator or a weak consistent iterator.

3. Design pattern

Know the advantages and disadvantages of common design patterns.

Be able to draw UML diagrams of common design patterns.

4. Multithreading

The difference and connection between Thread and Runnable, what happens when you start a thread multiple times, and what is the state of the thread.

If there are four threads of Thread1, Thread2, ThreaD3 and Thread4 to count the size of the four disks C, D, E and F respectively, and all the threads are counted and handed over to Thread5 threads to do a summary, how should it be realized?

How many thread pools are commonly used? What are the differences and relationships between these thread pools? What is the implementation principle of thread pool?

The difference between synchronized and ReentrantLock, the common method and static method of synchronized lock, the principle and troubleshooting method of deadlock, and so on.

5. JDK source code

If you want to get a high salary, you must read the JDK source code and summarize the more important source codes:

List, Map, Set implementation class source code

Source code of ReentrantLock and AQS

The implementation principle of AtomicInteger, mainly can explain the CAS mechanism and how AtomicInteger is implemented by CAS mechanism.

Implementation principle of Thread Pool

The methods in the Object class and the role of each method.

6. Database

The difference between union and union all, left join, several indexes and their differences, database performance optimization.

7. Data structure and algorithm analysis

Array, linked list is the foundation, stack and queue a little deeper but not difficult, the tree is very important, the more important trees AVL tree, red-black tree, can not understand their specific implementation, but to know what is a binary search tree, what is a balanced tree, the difference between AVL tree and red-black tree.

8. Java virtual machine

Memory layout of Java virtual machine

GC algorithm and several garbage collectors,

Class loading mechanism, that is, the parent delegation model

Java memory model

Happens-before rule

Rules for the use of volatile keywords

9. Some problems in Web

Several implementation methods of distributed Session

The difference and connection between Session and Cookie and the implementation principle of Session.

The difference of get/post, the difference of forward/ redirection, the realization principle of HTTPS

Consistent Hash algorithm

II. Java interview question 1 Java basis

1.1 basic Java syntax

Object-oriented features

The limits of four modifiers in java

The difference between overloading and rewriting

What's the difference between abstract classes and interfaces?

Java basic data type

What's the difference between int and Integer?

Talk about the difference between & and &

The difference between final, finally and finalize

Methods in the Object class

The difference between equals and =

1.2 Java common collections

The difference between List and Set

The difference between List and Map

The difference between Arraylist and LinkedList

The difference between ArrayList and Vector

Will there be a problem if the ArrayList is deleted during the loop?

The difference between HashMap and Hashtable

The difference between HashSet and HashMap

HashMap source code, implementation principle

What is the expansion of HaspMap? why is it all the size of 2 to the Nth power?

The difference between HashMap,HashTable,ConcurrentHashMap

1.3 Java IO and NIO

What is a Bit, what is a Byte, what is a character (Char), what are their lengths, and what are their differences

There are several types of streams in java

What is the difference between character stream and byte stream

What is java serialization and how to implement java serialization?

The difference between IO and NIO

What's the difference between ByteBuffer and StringBuffer?

What is the memory-mapped cache

What is the difference between a direct buffer and an indirect buffer

Native NIO has epoll bug in JDK version 1.7

2 multithreading

2.1 basic concepts of threads

The difference between threads and processes

What are the ways to create a thread

Understanding of Callable and Future

Life cycle of a thread

Analysis of ThreadLocal principle

The difference between sleep and wait

The difference between notify and notifyAll

What's the difference between sleep (), join () and yield ()?

2.2 Thread pool

Why use thread pools

Several implementation methods of thread pool

Implementation principle of Thread Pool

Stop method of thread pool

2.3 Lock

The usage of synchronized keyword, advantages and disadvantages

The difference between synchronized and lock

The function and principle of volitile keyword

The concept and understanding of CAS

Pessimistic lock and optimistic lock

The use and implementation principle of reentrant lock

3 database

Database lock, row lock

The nature of things

Considerations for the use of MySQL indexes

The principle of database index

Common Storage engine of MySQL Database

4 algorithm

Sorting algorithm

B + tree

Red and black tree

5 frame

What's the difference between BeanFactory and ApplicationContext?

Life cycle of Spring Bean

The principle of singleton implementation of Spring

How to implement Spring IOC

Talk about Spring AOP.

Principle of Spring AOP implementation

Dynamic agents (cglib and JDK)

What design patterns are used in the Spring framework

MVC design idea

Spring MVC running process

How does the Controller of SpringMVC handle parameters

6 network

The model of computer network

TCP,UDP distinction

Three handshakes, four waves, why four waves?

Long connection and short connection

Is the connection pool suitable for long connections or short connections?

Https principle

At this point, the study of "what is the content of learning Java language" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.