Java

Recently in dealing with a requirement, the requirements are described as follows: A simple process for a field of data queried in a database. Handled by: If the value of the field (the value range 0~4, possibly null) equals 0, then the default

Ha ha. People usually use the phone book. Here's a simple phone book that uses Java to simulate ...First, give the abstract class of the contact.Package net.itaem.po;/** * * Phone person's information * */public class User {private string

Java implementation of FTP file and folder upload and download http://www.cnblogs.com/winorgohome/archive/2016/11/22/6088013.html FTP is the abbreviation for file Transfer Protocol (document Transfer Protocol), and Chinese is called

Java multithreaded programming, there are many thread security issues, as to what is thread safety, it is difficult to give an easy-to-understand concept, as in the Java Concurrency programming practice, said:It is difficult to write a definition of

When the CSV file is output from HTTP response, it is set to UTF8 without the defaultBOM, but Windows Excel uses the BOM to confirm the UTF8 encoding, all need to write the BOM to the beginning of the file. Microsoft's use of the BOM in UTF-8 is

some time ago in the Kafka QQ Group was asked about this--about how Java consumer dynamically modify topic subscription issues. It's really a good question to think about it, because if you simply hold the consumer instance in another thread and

The following information is transferred from http://tutorials.jenkov.com/java-concurrency/concurrency-vs-parallelism.html (using Google Translate):Terminology concurrency and parallelism are commonly used in multithreaded programs. But what exactly

Symmetric encryption algorithmDefinition: In the symmetric encryption algorithm, the sender of the data sends the plaintext (raw data) and the encryption key (Mi Yue) together with a special encryption algorithm, which makes it into a complex cipher

Note: This article is reproduced from http://www.cnblogs.com/huajiezh/p/5790928.html, the copyright belongs to its all! Summary of common questions in JavaFirst, the Java Foundation1. Why is the string class final?2, HashMap The source code, the

Import Java.io.ioexception;import java.util.*;p Ublic Class A {public static void main (string[] args) throws IOException {Scanner sc=new Scanner (system.in); System.out.println ("Please enter a string"); String Str=sc.nextline (); boolean

There are a lot of people on the Internet to discuss the exception capture mechanism in Java try...catch...finally The finally statement in the block is bound to be executed? A lot of people say no, of course their answer is right, after I have

Don't be influenced by the idea of Java programming, the terminology in computer science- passed by reference (pass-by-reference). Do not make yourself a self-talk personal language.These terms are also not specific to Java, and you should not learn

The following is referenced from http://wiki.jikexueyuan.com/project/java/data-structures.html:The data structure provided in the Java Toolkit is very powerful and has a lot of functionality. These data structures contain the following interfaces

The For-each loop is also called an enhanced for loop, or a foreach Loop.The For-each loop is a new feature of JDK5.0 (other new features such as generics, auto-boxing, etc.).The addition of the For-each loop simplifies the traversal of the

New Features of Servlet3.0 (Tomcat7.0 and later) and new features of servlet3.0@ WebServlet  Function After a Servlet is created in Eclipse, Eclipse does not automatically generate the ing information of the Servlet in web. xml, but adds the

Dynamic Proxy Case 1: use proxy dynamic Proxy to enhance the method. Use Case proxy Dynamic proxy Case 1:/* Requirement: use Proxy dynamic Proxy to enhance the MethodQuestion:1. Define the interface Fruit with the addFruit Method2. Define

Java basics-I/O (3) and java basics I/O 1. Pipeline Flow Demo: PipedInputStream and PipedOutputStream Note: Pipeline streams are not recommended in one thread because the data written to the output stream is saved to an array of 1024 bytes in the

Use Listener to record the cumulative number of visitors, the maximum number of simultaneous online users, and the number of currently logged-on users. 1. The global statistics variable class of the website. Only global variables are defined. 1

Java polymorphism understanding and java polymorphism understanding Implementation of polymorphism in Java What is polymorphism The following are three necessary conditions for the existence of polymorphism, which require that everyone be able to

Poi package conflict (excel), poi package conflict excel 1. jar packages Involved poi (1) poi-3.14.jar (HSSF) Dependency: commons-logging-1.2.jar, log4j-1.2.17.jar, commons-codec.1.10.jar, junit.4.12.jar, hamcrest-core.1.3.jar (2) poi-ooxml-3.14