Thank you for participating in our interview:
Below is a summary of some pre-interview and technical reference questions that we hope will help you.
First, you need to prepare a job-related self-introduction, including the following:
1. Several years of Java development experience, roughly outline what types of projects have been done, and how long the experience is (such as Internet finance, Internet e-commerce, traditional back-office, etc.)
2. Select 1 to 2 recent key projects to introduce in detail;
What position do you mainly hold, what is the work content, you can also briefly introduce the composition of the team, and what role do you belong to (such as architecture construction, core code writing, mainly doing interface development, etc...)
What is the technology of the project (please specify the development environment, framework, development tools, database, etc.), if there are some more innovative technologies, please specify
How about the project results (whether it is online or not, how is the user's use effect, etc.)
Personal technical summary / outstanding achievements (such as how you deal with technical problems; what constructive suggestions do you have to improve the project; whether the project technology is insufficient, what do you think you would do if you do)
Secondly, you need to look at your resume and review the technical points written in your resume (especially those who are proficient and familiar).
Many times, technical interviewers will ask questions from shallow to deep based on the technical points written in your resume.
Finally, the following are some Java basic technical reference questions we provide you. There are no answers, you need to prepare yourself ~ I wish the interview a success, come on!
Database related: Find the names of students with an average score greater than 60 and their personal average.
The difference between pass-by-value and pass-by-reference;
The difference between overloading and rewriting
IOC of spring framework, personal understanding of AOP
Strutsstruts2springmvc framework underlying implementation and their differences;
First-level cache and second-level cache of hibernate framework
What is the java class loader, http protocol
Java memory mechanism
Java data structures
Redis basic data types
Spring transaction propagation mechanism
The role of beans
What design patterns have you used?
The difference between singleton mode and multiple instances
What is a factory pattern, what are the types of factory patterns, and under what circumstances are they used?
What is the reflection mechanism of java
What is a dynamic proxy
The 7-layer implementation of http (or what is the 3-way handshake)
What are the ways to prevent sql injection
How to deal with high concurrency
What is a synchronization lock
What is optimistic locking
What is pessimistic locking
How to optimize sql; what is the execution mode of sql; how to know how sql is executed?
spring configuration file
Encryption of data interaction
Memory allocation
1. What is the working mechanism of the data connection pool?
When the J2EE server is started, a certain number of pool connections will be established, and it will maintain no less than this number of pool connections. client program
When a connection is required, the pool driver returns an unused pool connection and marks it as busy. If there is no idle connection currently, the pool driver will create a certain number of connections, and the number of new connections is determined by configuration parameters. When the used pool connection call completes, the pool driver marks the connection as free, and other calls can use the connection.
In the implementation, the returned Connection is the proxy of the original Connection. The close method of the proxy Connection does not actually close the connection, but returns the Connection object it proxied to the connection pool.
2. What is the difference between an interface and an abstract class?
Java provides and supports creating abstract classes and interfaces. Their implementations have something in common, the differences are:
All methods in an interface are implicitly abstract. An abstract class can contain both abstract and non-abstract methods.
A class can implement many interfaces, but can only inherit from one abstract class
For a class to implement an interface, it must implement all the methods declared by the interface. However, a class may not implement
All methods declared by an abstract class, of course, in this case the class must also be declared abstract.
An abstract class can implement an interface without providing an implementation of the interface's methods.
Variables declared in a Java interface are final by default. Abstract classes can contain non-final variables.
Member functions in Java interfaces are public by default. Member functions of abstract classes can be private,
protected or public.
Interfaces are absolutely abstract and cannot be instantiated. An abstract class also cannot be instantiated, however, if it contains
If the main method is included, it can be called.
3. Briefly explain the several available states of the thread?
During execution, a thread can be in the following states:
Ready (Runnable): The thread is ready to run, it may not be able to start execution immediately.
Running (Running): The process is executing the code of the thread.
Waiting (Waiting): The thread is in a blocked state, waiting for the end of external processing.
Sleeping: The thread is forced to sleep.
I/O blocking (BlockedonI/O): waiting for the I/O operation to complete.
Blocked on Synchronization: Waiting to acquire a lock.
Dead: The thread has finished executing.
4. What is the difference between HashMap and Hashtable?
Both HashMap and Hashtable implement the Map interface, so many features are very similar. However, they
There are the following differences:
HashMap allows keys and values to be null, while Hashtable does not allow keys or values to be null.
Hashtable is synchronous, while HashMap is not. Therefore, HashMap is more suitable for single-threaded environment,
Hashtable is suitable for multi-threaded environment.
HashMap provides a collection of keys that the application can iterate over, so HashMap is fail-fast. another
On the one hand, Hashtable provides an enumeration of keys (Enumeration).
Hashtable is generally considered a legacy class
5. What are the nine built-in objects of jsp?
application page request response session exception out config
pageContext
Finally, here are some learning materials I collected about programmers interviewing Java, follow me, and reply by private letter: 'Java' to get:
