java code snippets for practice

1: Using Swetakeqrcode to generate two-dimensional code in a Java projecthttp://swetake.com/qr/or Http://sourceforge.jp/projects/qrcode/downloads/28391/qrcode.zip.This was written by the Japanese and generated by our common square QR code.Can be in Chinesesuch as: 5677777GHJJJJJ2: Use barcode4j to generate barcodes and QR codesBARCODE4J website: http://sourceforge. NET/projects/barcode4j/BARCODE4J is a two-

easily accessible to the current thread instance, it is threadlocal.Three: Threadlocal's application scenarioThreadlocal has such scenarios as connection pooling management, session management, and so on.In the management of the connection pool, when we need to get a connection, we should give a different connection for each fetch. In a Web application, a request is managed by a thread pool, which means that the behavior of getting a connection is not a single-threaded behavior, so we'd better

released outside. The birds are gone, and the birds are still alive. Design Principles Pages Principle 9 To find the changes, to separate them, and not to mix it up without change. 11 Programming for interfaces, not for implementation. 23 Multi-use combination, less inheritance 53 A loose coupling effort between interacting objects 86 Open extensions, close modifications

(patterns) and text (text) in the matching process with known information. The posting bad character algorithm (Bad-character) and the Good suffix Algorithm (good-suffix), which are recommended above, are used to determine how many bits to move (shift) or move, not to elaborate here. Full algorithm: because this article is mainly used to help remember, not the persuasion to tell you how to implement this algorithm. So I put the complete code (

During this time, I was learning about Android Application Development. I was thinking that since Java was used for development, it should be a good decompilation to get the source code. Google is actually very simple. Here is my practice process. I solemnly declare that the purpose of the post is not to crack the software of other people, but it is completely a

The memory management mechanism in a Java program is done through GC , "When an object is created, it is placed in the JVM 's heap memory and will be reclaimed by the JVM in heap memory when the object is never applied." The object being created cannot be regenerated, and there is no way to release it through the program statement "(this is the definition mentioned in the Java GC mechanism, hehe, still vagu

public abstract void wakeup(); Selector (Selector) is a Java NIO system that can detect one or more NIO channels and determine whether to prepare for read/write events. In this way, a single thread can manage multiple channels to manage multiple network connections. The advantage of using a single thread to process multiple Channels is that fewer threads are needed to process Channels. In fact, you can use only one thread to process all the channels

11. Multiplication and division using shift operationsFor example:for (val = 0; Val The shift operation can greatly improve performance, because at the bottom of the computer, the bitwise operation is the most convenient and fastest, so it is recommended to modify:for (val = 0; Val Although the shift operation is fast, it may make the code less understandable, so it's best to add the appropriate comments.12. Do not constantly create object references

(this);} public boolean containsPoint(Point p) {return pPolygon.containsPoint(this, p);} . } Among them, Ppolygon is: class pPolygon { static public int computePerimeter(Polygon polygon) {...} static public boolean isConvex(Polygon polygon) {...} static public boolean containsPoint(Polygon polygon, Point p) {...} } As you can see from the name Ppolygon of the class, the process encapsulated by the class is primarily related to objects of type polygon. The P in front of the first name indicate

Java Solar System Small game analysis and source code-20150809Recently looked at some object-oriented knowledge, and then followed the teacher's explanation to do a solar system of the planets around the sun to the game, to practice consolidating the knowledge of recent studies:Knowledge points: Inheritance of classes, overloading and rewriting of methods, polymo

Java Solar System Small game analysis and source code-20150809Recently looked at some object-oriented knowledge. Then follow the teacher's commentary made a solar system of the planets around the sun to the game, to practice consolidating the knowledge of recent studies:Knowledge points: Inheritance of classes, overloading and rewriting of methods, polymorphism,

Reprinted from: http://blog.csdn.net/java_cxrs/article/details/3860870After a few days of practice and research finally can write a tank war game, after writing this program feel a lot of harvest, the knowledge of Java has a certain growth, and then prepare to continue to write a few small projects to practice J2SEBecause the

Objective:KMP algorithm is a kind of string matching algorithm, which is discovered by Knuth,morris and Pratt simultaneously (called KMP algorithm). The key of KMP algorithm is to reduce the number of matches between the pattern string and the main string so as to achieve fast matching by using the information after the match failure. The popular practice is to implement a next () function, which itself contains local matching information for the patt

Special comments in Java codeTODO: + description : The function code is to be written, and the function to be implemented is briefly explained in the description.fixme: + description : The code needs to be corrected, even the code is wrong, not working, need to repair, how to fix it in the description of the brief desc

{@SuppressWarnings ("resource") public static void main (string[] args) {try {///1. Create a server-side socket, that is, ServerSocket, specify the bound port and listen for this port serversocket serversocket = new ServerSocket (8888); Socket socket = NULL; SYSTEM.OUT.PRINTLN ("Server started, waiting for client to connect ..."); Loop listening for a connection waiting for a client while (true) {//2. Call the Accept () method to start listening, waiting for the client's connection socket =

) { g.drawimage (bg, 0, 0, null); Sun.draw (g); Earth.draw (g); Mars.draw (g); } public static void Main (string[] args) { new Solarframe (). Launchframe (); } Star.java Package solar; Import Java.awt.Graphics; Import Java.awt.Image; Import util. Gameutil; public class Star {public Image img; public double x,y; int w,h; public void Draw (Graphics g) { G.drawimage (img, (int) x, (int) y, null); Public Star (

structure is a two-way list. the method of searching for elements by subscript node (int index), first determine which side is closer to the head and tail, and then start looking from the nearer end. 3. can contain null elements.4. The iterator uses the Fail-fast design idea. This is similar to the ArrayList.5. The element is in node nodes, where node is the inner class. When you look at implementing code, you can use paint to help understand that th

Recently doing performance analysis, using Eclipse's TPTP to do performance analysis, although the earlier known frequent call method is more cost-performance, after all, need to maintain a call stack, the specific theory has been blurred, take practice to narrate a problem. Have the following code /** * Get cache Define list * * @return listFrom the above code

end, such as the following code.Attention:In practice, if the Linux command fails on a Linux server, such as the not found command, it is executed, and the code will continue to go down. So make sure the command is correct, or use the return value to judge! The return and not called return values of the call WAITFOR () are different types.Such a download method can only rely on the download to the local MA

"Now programming is like doing scientific research on the parts of the process that you need to solve. ”--gerald Sussman Designing and maintaining good software is like a never-ending struggle to resist complexity. Code paths and components for any size-sufficient application can quickly grow into a dizzying combination of explosions.It's not a simple thing.When you deploy a platform similar to Heroku and AWS, a single-server Web application beco